Features of K126 carburetors - device, tuning and adjustment. K126 carburetor device, adjustment and repair of K 126 for UAZ adjustment

The era of carburetor technology is long gone. Today, fuel enters the car's engine under electronic control. However, cars that have carburetors in their fuel system still remain. In addition to retro cars, there are still quite working "horses" - UAZs, as well as classics from the Togliatti Automobile Plant. And that means that the ability to understand the device, carry out maintenance, repair the carburetor remains in price.

This article will focus on the K126G carburetor. Adjusting the K126G carburetor is a delicate undertaking that requires certain skills and a good knowledge of its composition and principles of operation. But first, let's remember a little about what a carburetor is.

About carburetor systems

So what is a carburetor? Translated from French carburation - "mixing". From here, the purpose of the device becomes clear - to create a mixture of air and fuel. After all, it is the fuel-air mixture that is ignited by the spark of a car candle. Due to their simple design, carburetors are now used on low-power lawnmower and chainsaw engines.

There are several varieties of carburetors, but everywhere the main components will be a float chamber and one or more mixing chambers. The principle of the float chamber is similar to the valve mechanism of the toilet bowl. That is, the liquid enters to a certain level, after which the locking device is activated (for a carburetor, this is a needle). The fuel enters the mixing chamber through the atomizer along with air.

The carburetor is a fairly thin device to set up. Adjustment of the K126G carburetor should be made at every maintenance and any problem. A properly tuned fuel-air mixture supply unit ensures even engine operation.

K126G carburetor device

The K126G carburetor is a typical representative of the two-chamber version. That is, the K126G contains a float and two mixing chambers. And if the first one works constantly, then the second one starts to work only in dynamic modes with sufficient load.

The K126G carburetor, the device whose adjustment and repair is described in this article, is quite popular for UAZ vehicles. The device is very unpretentious in operation and resistant to debris.

The float chamber K126G has a viewing window, which can be used to determine the fuel level. The carburetor incorporates several subsystems:

idle move;
starting a cold engine;
accelerator pump;
economizer.

The first three work only in the primary chamber, and a separate atomizer is provided for the economizer system, which is output to the air channel of the second chamber of the carburetor. The general control of the device is carried out using the "suction" system and the accelerator pedal.

Applicability K126G

The carburetor marked "K126G" was installed and is still being serviced on Gaz-24 Volga and UAZ vehicles, with mainly UMZ-417 engines. UAZ car owners especially love this model for its unpretentiousness and ability to work even with clogged fuel.

With minor modification (drilling a hole), K126G is installed on UMZ-421 engines. And it can be both UAZ and Gazelle. The predecessor of the K126G can be considered the K151, and the next model is the K126GM.

Adjusting the K126G carburetor is the most popular question among carburetors. But first, let's look at the various problems that can happen with the K126G.

Possible malfunctions

All malfunctions of the described system are either visually visible or easy to check. One of the main problems is the unstable operation of the engine at idle, or there are none at all. The K126G carburetor, whose fuel consumption adjustment is normal, allows the engine to idle without any problems.

The second point, which shows that the device is faulty and requires adjustment, is an increase in fuel consumption. There may be several reasons, so adjusting and adjusting the carburetor does not always help.

Scheduled regular cleaning of all constituent elements can solve the problem. Incomplete cleaning is also possible with the carburetor not removed from the car, but it is undesirable. K126G, like any mechanical device, prefers good care.

Carburetor adjustment K126G

The need to adjust the carburetor may arise for various reasons. This may be scheduled maintenance or troubleshooting issues. Moreover, a simple adjustment according to the instructions is quite simple to perform. The downside is that it does not always help in the decision. Experienced mechanics with extensive experience in carburetor repair do not take up work without adjusting the valves.

In order for the air-fuel mixing device to function without interruption and not require constant adjustment, timely maintenance is necessary. It is enough to make an elementary inspection for leakage and tightness and flush the carburetor at least partially. Sometimes it is necessary to check the fuel level in the float chamber, as well as the throughput of the jets, both fuel and air.

If we approach the issue systematically, then it is necessary to distinguish the following types of carburetor settings:

idle move;
fuel level in the chamber with a float;
economizer valve.

Adjusting the K126G carburetor on a UAZ most often involves adjusting a specific idle speed. So, let's consider the sequence of actions to restore auto stability at idle.

Instructions for adjusting idling K126G

Adjustment of stability of work of the engine is carried out by two screws. One determines the amount of the fuel-air mixture, and the second determines the quality of its enrichment in K126G. Carburetor adjustment, the instructions of which are given below, is carried out in stages:

With the car turned off, tighten the mixture enrichment screw until it stops, and then unscrew it by 2.5 turns.
Start the car engine and warm it up.
With the first screw, achieve accurate and stable engine operation at about 600 rpm.
With the second screw (enrichment of the mixture), gradually deplete its composition so that the engine continues to work stably.
With the first screw we increase the number of revolutions by 100, and with the second we decrease them by the same amount.

The correctness of the adjustment is checked by increasing the speed to 1500 and then closing the throttle. In this case, the turnover should not fall below the permissible values.

Adjusting the fuel level in the float chamber

Over time, it may happen that the level of gasoline in the float chamber changes. Normally, it should fluctuate within 18-20 mm from the bottom surface of the connector, which is determined through the viewing window of the carburetor. If visually this is not the case, then it is necessary to make an adjustment.

Changing the fuel level in the K126G chamber is carried out by bending the tongue of the float lever. This is done very carefully, trying not to damage the seal washer made of special gasoline-resistant rubber.

Variety of manufacturers

Among the manufacturers of the K126G carburetor there were:

"Solex";
"Weber";
"Pekar".

Today, it is Pekar that has gained the most popularity. Users note in the reviews more stable operation, as well as high dynamic qualities with economical fuel consumption in the region of 10 liters per 100 km. It is worth noting that the Pekar K126G carburetor is adjusted in the same way as above.

Advantages and disadvantages of K126G

The K126G carburetor is quite popular with UAZ owners. It is appreciated for a number of advantages that are not available in more modern models:

stable operation in the presence of clogging;
unpretentiousness to fuel quality;
sufficient savings.

The K126G carburetor, whose mixture quality is adjusted regularly, will work without any problems. Simplicity of a design - a guarantor of reliability. In this case, this will correspond, but subject to the planned Maintenance.

K126G has one unpleasant drawback. In case of overheating, the body of the device may be deformed. This happens when the carburetor threaded connections are overtightened.

Conclusion

As experience shows, adjusting the K126G carburetor is not such a difficult issue. And timely maintenance of the device will significantly extend its life. All this, together with the unpretentiousness of the K126G, attracts owners of carbureted cars.

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Adjusting the carburetor K-126 on UAZ

The "golden age" of carburetor engines has long passed. Today, all vehicle systems are electronically controlled. Nevertheless, there are people who appreciate their "war horses" UAZ with a carburetor for simplicity and reliability. If you are one of them, this article is for you. We will tell you how to install the K-126GU carburetor on a UAZ.

Motorists appreciate UAZ with a K-126GU carburetor for simplicity and reliability

Device and technical characteristics of K-126GU

The two-chamber carburetor K-126GU with a falling fuel mixture flow is the basic model for UAZ vehicles. For proper configuration, you need to have an idea about the device, parameters and principles of operation of the unit.

Essential elements:

two working chambers for mixing fuel with dosing systems;
economizer;
accelerator pump;
idle device.

To properly configure the K-126GU carburetor, you need to know about the device, parameters and principles of operation of the unit

The unit allows uninterrupted operation in all possible modes. It should be noted that the K-126 has a simple and reliable design. With proper tuning, it provides fuel consumption per 100 km:

for urban conditions 13 l;
on the highway 11 l.

Installation

First, remove the air filter. Next, take pictures one by one:

damper drives;
hoses (fuel supply and vacuum corrector vacuum selection).

The K-126GU carburetor is simple, reliable and unpretentious in maintenance

The unit is mounted on the flange of the intake manifold of the motor. We fix the carburetor with four nuts. Additionally, spring washers are used. We check the integrity of the rubber gasket, if necessary - change it. At the final stage, we attach the damper actuators and nozzles.

Setting order:

we check the tightness of the unit (special attention to the areas of attachment of hoses, plugs and gaskets). If we find a fluid leak, we fix the problem;
we pump fuel (6–8 times with a manual fuel pump);
close the choke, start and warm up the engine;
as the motor warms up, gradually open the damper;
at the moment when the antifreeze temperature reaches +40 ° C, fully open the damper;
until it stops, we screw in the screw that regulates the quality of the fuel mixture;
unscrew the “quality” screw by 5 turns;
bring the temperature of the liquid to 90 ° C;
increase the speed of the crankshaft to the maximum possible amount;
smoothly tighten the screw for adjusting the amount of the fuel mixture until interruptions in the operation of the engine begin;
unscrew the “quantity” screw by half a turn;
check engine performance. We press the gas pedal, and then abruptly release it. If the engine stalls - increase the speed.

Conclusion

Despite its "venerable age", the K-126 carburetor continues to be used. The reasons are simplicity, reliability, unpretentiousness in maintenance. A minimum of effort for maintenance, and the unit will work smoothly for years.

Maybe you know some special methods for setting up a K-126 carburetor? Share your experience in the comments. Transfer your skills to young car enthusiasts.

CarExtra.ru

Carburetor K-126

Page 1 of 3

The K-126 carburetor is installed on the GAZ-21, GAZ-24, GAZ-53, GAZ-66 engines, etc.

Very simple and reliable carburetor.

A feature of the K-126B carburetor is that all jets can be washed and blown without disassembling the carburetor.

The carburetor has two mixing chambers: primary and secondary. The primary chamber operates in all engine modes.

The secondary chamber is activated or under heavy load (after about 2/3 of the primary chamber throttle stroke).

To ensure uninterrupted operation of the engine in all modes, the carburetor has the following metering devices: a cold-running system for the primary chamber, an adapter system for the secondary chamber, the main metering systems for the primary and secondary chambers, an economizer system, a cold engine start system and an accelerator pump system.

All elements of dosing systems are located in the body of the float chamber, its cover and the body of the mixing chambers.

The body and cover of the float chamber are cast from zinc alloy.

The body of the mixing chambers is cast from aluminum alloy.

Sealing cardboard gaskets are installed between the body of the float chamber, its cover and the body of the mixing chambers.

In the body of the float chamber there are: two large 6 and two small diffusers 7, two main fuel jets 28, two air brake jets 21 of the main metering systems, two emulsion tubes and, located in the wells, fuel 13 and air jets of the idle system, an economizer and guide sleeve 27, accelerator pump 24 with pressure and check valves. The atomizers of the main dosing systems are led into small diffusers of the primary and secondary chambers. The diffusers are pressed into the body of the float chamber, in the body of the float chamber there is a window 15 for monitoring the fuel level and the operation of the float mechanism. All channels of the jets are equipped with plugs to provide access to them without disassembling the carburetor. The idle fuel jet may be turned out from the outside, for which its body is brought out through the cover up.

Rice. 1

In the cover of the float chamber there is an air damper 11 with a semi-automatic drive. The air damper drive is connected to the throttle valve axis of the primary chamber by a system of levers and rods, which, when starting a cool engine, open the throttle valve to an angle necessary to maintain the starting engine speed. The secondary throttle valve is tightly closed. This system consists of an air damper drive lever, which with one shoulder acts on the air damper axle lever, and with the other through a rod on the idle throttle lever, which, turning, presses the primary chamber damper and opens it.

A float mechanism is attached to the carburetor cover, which consists of a float suspended on an axle and a fuel supply valve 30. The carburetor float is made of 0.2 mm thick brass sheet. The fuel supply valve is collapsible, consists of a body and a shut-off needle. Valve seat diameter 2.2 mm. The cone of the needle has a special sealing washer made of a fluorine rubber compound. The fuel entering the float chamber passes through the mesh filter 31.

In the body of the mixing chambers there are two throttle valves 16 of the primary chamber and the secondary chamber, an adjusting screw 2 of the idle system, a toxicity screw, idle system channels that serve to ensure coordinated operation of the idle system and the main dosing system of the primary chamber, a hole 3 for supplying vacuum to a vacuum ignition timing regulator, as well as a transitional system of the secondary chamber.

The carburetor idle system consists of a fuel jet 13, an air jet and two holes in the primary mixing chamber (upper and lower). The lower hole is equipped with a screw 2 for adjusting the composition of the combustible mixture. The idle fuel jet is located below the fuel level and is connected after the main jet of the primary chamber. The fuel is emulsified by an air jet. The required performance of the system is achieved by the idle fuel jet, air brake jet, as well as the size and location of the vias in the primary mixing chamber.

The main dosing system of each chamber consists of large and small diffusers, emulsified tubes, main fuel and main air jets. The main air jet 21 regulates the flow of air into the emulsion tube 23 located in the emulsion well. The emulsion tube has special holes designed to obtain the required performance of the system. The idling system and the main metering system of the primary chamber provide the necessary fuel consumption in all main engine operating modes. The economizer system consists of a guide sleeve 27, a valve 23 and an atomizer 19. The economizer system is activated until the throttle valve of the secondary chamber is fully opened. It should be noted that, in addition to the economizer system, the main metering systems of both chambers operate at full load and very little fuel continues to flow through the idle system.

The accelerator pump system consists of a piston 24, a drive mechanism 20 for the inlet and discharge (outlet) valves, and an atomizer 12 brought into the air pipe of the primary chamber. The system is driven by the throttle axis of the primary chamber and operates when the vehicle is accelerating. On the axis of the throttle valve of the primary chamber, the lever 4 of the drive is rigidly fixed. Also rigidly fixed on the axle is the leash of the backstage 25. The backstage is freely mounted on the axis of the damper 16 and has two grooves. In the first of them, the leash moves, and in the second - a finger with a roller of the lever 26 of the drive of the axis 8 of the secondary damper mounted on it. The shutters are held in the closed position by springs attached to the axis of the primary chamber and the axis of the secondary chamber. The link 25 also constantly tends to close the shutter of the secondary chamber, since it is acted upon by a return spring fixed on the axis of the primary chamber. When the lever 4 of the drive of the axis of the primary chamber moves, the leash of the lever of the primary chamber first moves freely in the groove of the wings 25 (thus, only the damper of the primary chamber opens), and after about 2/3 of its stroke, the leash begins to turn it. The link 25 of the secondary damper actuator opens the secondary throttle. When the gas is released, the springs return the entire lever system to its original position.

The carburetor must be flushed in clean unleaded gasoline or acetone, followed by a compressed air purge.

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Carburetor adjustment: perform on K 126 on UAZ

Unit for UAZ

The power system for gasoline engines is represented by high-precision injection, which not only achieves excellent mixing quality of the working mixture and its complete combustion, but also a significant reduction in fuel consumption. At the same time, a number of carburetors are still used in engines on UAZ vehicles to form a fuel mixture. Motor maintenance problem various types carburetors is still relevant today.

Among the carburetors UAZ 469 and other related models there are a wide variety of modifications. The main types of devices for the formation of a fuel mixture:

More often than others, the K 126 carburetor is used. Before proceeding with the adjustment of operating parameters, you should consider the device of each unit.

The K-126 carburetor is installed on the GAZ-21, GAZ-24, GAZ-53, GAZ-66 engines, etc.

Very simple and reliable carburetor.

A feature of the K-126B carburetor is that all jets can be washed and blown without disassembling the carburetor.

The carburetor has two mixing chambers: primary and secondary. The primary chamber operates in all engine modes.

The secondary chamber is activated or under heavy load (after about 2/3 of the primary chamber throttle stroke).

All elements of dosing systems are located in the body of the float chamber, its cover and the body of the mixing chambers.

The body and cover of the float chamber are cast from zinc alloy.

The body of the mixing chambers is cast from aluminum alloy.

Sealing cardboard gaskets are installed between the body of the float chamber, its cover and the body of the mixing chambers.

A float mechanism is attached to the carburetor cover, which consists of a float suspended on an axle and a fuel supply valve 30. The carburetor float is made of 0.2 mm thick brass sheet. Fuel supply valve - collapsible, consists of a body and a shut-off needle. Valve seat diameter 2.2 mm. The cone of the needle has a special sealing washer made of a fluorine rubber compound. The fuel entering the float chamber passes through the mesh filter 31.

The carburetor must be flushed in clean unleaded gasoline or acetone, followed by a compressed air purge.

The state of the main parts and assemblies entering the assembly

All channels of body parts must be thoroughly flushed and blown with compressed air. It is allowed to repair breaks of fastening flanges that do not capture internal cavities and channels by welding.

The surfaces of the connecting flanges of the body parts must be flat without nicks and irregularities.

When checked on a slab, the flatness should not exceed 0.1 mm.

The performance of the jets before installation in the carburetor must be checked on the device model NIIAT-528 or another device that allows you to check the performance of the jets:

Main air jet Ø 0.8 +0.06mm;

Idling fuel jet Ø 0.75 +0.06mm;

Air idle jet Ø 1.5 +0.06mm;

Economizer nozzle Ø 0.7 +0.06mm;

Accelerator pump nozzle Ø 0.6 +0.05mm.

The performance value of the K-126B carburetor jets should be within the following limits:

Main fuel jet - 340 ± 4.5 cm 3 / min;

Diaphragm mechanism jet - 75 ± 3 cm 3 / min;

The nozzle of the diaphragm mechanism is vacuum - 310 ± 7 cm 3 / min.

The size of the emulsion holes in the mixing chamber:

Upper Ø 1.0 +0.06 47;

Bottom Ø 1.3 +0.06mm.

The thread of the jets should not have nicks.

The economizer valve must be sealed. The tightness must be checked with water at a pressure of 1200 mm of water. Art. no more than 4 drops per minute are allowed to flow under the valve. The valve stem must protrude from the body within 1.1 + 0.3 mm.

The diffuser body must be intact, without breaks and cracks.

The float must not have holes or dents. It must be tested for leaks by immersion in hot water. The appearance of air bubbles in a serviceable float is not allowed.

The weight of the float must be within 13.3 ± 0.7 g.

The fuel supply valve must be leak tested with a vacuum of 100 mmHg. Art., through the water; at the same time, leakage of no more than 10 drops per minute is allowed.

Dismantling the carburetor

The carburetor is disassembled to clean the float chamber for changing jets and mating parts in case of violation of their landings.

Disassemble the carburetor in the following order:

Unpin and remove one end of the low speed link from the hole in the lever;

Unscrew the seven screws securing the float chamber cover, remove the cover, being careful not to damage the cardboard gasket under it;

To take out, an axis of a float and to remove a float. Remove the fuel valve needle together with the spring;

unscrew the fuel valve body together with the paronite gasket. It is not recommended to unnecessarily remove the air damper. To remove the damper, unscrew the two screws securing it, then unscrew the screw securing the drive lever bushing, remove the lever together with the bushing and spring. Remove the choke shaft assembly with lever and return spring.

Unscrew the filter plug, release the paronite gasket and remove the strainer;

Next, proceed to disassemble the float chamber. Remove the cotter pin from the accelerator pump drive clevis. Carefully holding the accelerator pump drive with your hand from above, release the drive rod from the lever mounted on the throttle axis, remove the earring. Remove the accelerator pump drive rod assembly with the piston and economizer drive from the carburetor body. It is not recommended to disassemble the accelerator pump drive. If it is necessary to replace the accelerator pump piston or for other reasons, unscrew the adjusting nuts of the accelerator pump and economizer rods and remove the rods by removing the springs;

Unscrew the plugs outside the housing, unscrew the main fuel jets of the primary and secondary chambers and the idle air jet;

To access the emulsion tubes, unscrew the main air jets of the primary and secondary chambers.

Remove the idle fuel jet and the economizer valve. Remove the delivery valve of the accelerator pump;

Loosen the large nut at the front of the body and carefully, so as not to damage the gasket, remove the sight glass of the float chamber;

- small diffusers are not allowed to be pressed out of the carburetor body;

Unscrew the four fastening screws and disconnect the mixing chamber from the float chamber. Take out the two large diffusers and the spacer between the chambers.

- Do not dismantle the mixing chamber unnecessarily. If the throttle axis oscillates in the bosses or the tightness of the dampers to the walls of the chamber is unsatisfactory, and the axial play of the damper in the open state exceeds 0.3 mm, then the mixing chamber should be disassembled.

To completely disassemble the mixing chamber, you should:

Unscrew the nut of the lever of the throttle axis of the primary chamber and two screws securing the cover of the drive mechanism;

Remove the drive lever and low speed lever with mounting washers, and mechanism cover;

Remove the link with the spring from the throttle axis of the primary chamber. Unscrew two screws each and remove the throttles of the primary and secondary chambers;

Remove the accelerator pump drive lever from the primary chamber throttle axis and the nut with washer from the secondary chamber axis;

Pull both shafts onto the housings while removing the return spring of the primary chamber shaft.

Assembly

The float should freely, without jamming, swing on its axis, while providing a needle stroke of at least 1.5 mm.

The fuel level in the carburetor float chamber should be 18.5-21.5 mm below the upper plane of the body and correspond to the marks on the carburetor body that are visible through the viewing windows.

To obtain the correct level in the float chamber, it is allowed to bend the float bracket.

The diaphragm mechanism must be sealed. The test is carried out on a special stand. With a vacuum of 1500-1700 mm of water, Art. no more than three bubbles per second are allowed. The cover of the diaphragm mechanism and the cover of the lever mechanism of the diaphragm drive must be sealed. The axis of the throttles must rotate freely without jamming in the bearings. The circumferential clearances between dampers and housings must not exceed:

For throttle valves - 0.06 mm;

For air dampers - 0.2 mm.

When the air damper is fully closed, the damper throttles must open at least 12° from their full open position.

Full engagement of the economizer valve must be at full throttle.

Trial

The assembled carburetor must be checked for the absence of leaks and the height of the fuel level in the float chamber on the device model NIIAT-355. At an overpressure of 0.3–0.32 kg/cm 2 for gasoline with a specific gravity of 0.720–0.750 g/cm 3, the fuel level in the float chamber should be 20 ± 1 mm to the plane of the carburetor connector.

The performance of the accelerating pump must be at least 10 cm 3 for 10 piston strokes.

Checking the complete inclusion of the economizer valve is carried out by measuring: the gap between the strap and the economizer drive nut, the distance between the upper plane of the carburetor cover and the upper plane of the bar.

The gap between the bar and the nut of the economizer drive rod at the position of the upper plane of the bar at a distance of 13 ± 0.2 mm from the upper plane of the float chamber connector should be 3 ± 0.2 mm.

The distance between the upper split plane of the carburetor cover and the upper plane of the bar should be 21.5 ± 0.2 mm.

Checking the operation of the diaphragm mechanism of the pneumocentrifugal speed limiter is carried out on a special stand.

The carburetor speed limiter when working with a reference sensor must provide automatic limitation of the engine crankshaft speed when it works with an air filter within:

According to the speed characteristic - 3200-3400 rpm;

At idle - 3450-3550 rpm.

All carburetors coming out of repair should be checked on the engine to determine their basic performance, providing:

Ease of starting the engine;

Stable operation of the engine at low idle;

No failures at work.

The minimum stable speed of the engine crankshaft when idling should be in the range of 400-500 rpm.

When checking the operation of the engine in various modes (with and without load), the carburetor must provide a smooth transition without failures from one engine operating mode to another.

Carburetor adjustment

The idle speed is adjusted with a stop screw 1 (Fig. 3), which limits the closing of the throttles, and two screws 2, 2, which change the composition of the working mixture, on a well-heated engine and with a good ignition system. Particular attention should be paid to the serviceability of the spark plugs and the correct gap in their electrodes.

When adjusting, it should be borne in mind that the carburetor is two-chamber and the composition of the working mixture in each chamber is regulated independently.

Starting the adjustment, tighten the screws 2 to the full, and then unscrew them by two turns each. Start the engine and set screw 1 to the smallest throttle opening at which the engine runs quite stably. Then lean the mixture with one of the screws 2, tightening it ¼ turn at each test until the engine starts to run intermittently. After that, the mixture is enriched by unscrewing screw 2 by ½ turn. Do the same operations with the second screw 2.

After adjusting the composition of the mixture, try to reduce the idle speed by unscrewing the stop screw 1 of the throttles, and then again deplete the mixture with both screws alternately, as indicated above.

To check the idle speed adjustment, sharply press the throttle control pedal and release it sharply. If the engine stops, then the number of revolutions must be increased with the throttle stop screw.

A properly adjusted engine should run steadily at 475 - 525 rpm.

This article will focus on the K126G carburetor. K126G is a delicate event that requires certain skills and a good knowledge of its composition and principles of operation. But first, let's remember a little about what a carburetor is.

About carburetor systems

K126G carburetor device

The K126G carburetor, the device whose adjustment and repair is described in this article, is quite popular for UAZ vehicles. The device is very unpretentious in operation and resistant to debris.

The float chamber K126G has a viewing window, which can be used to determine the fuel level. The carburetor incorporates several subsystems:

idle move;
starting a cold engine;
accelerator pump;
economizer.

Applicability K126G

With minor modification (drilling a hole), K126G is installed on A, it can be either a UAZ or a Gazelle. The predecessor of the K126G can be considered the K151, and the next model is the K126GM.

Adjusting the K126G carburetor is the most popular question among carburetors. But first, let's look at the various problems that can happen with the K126G.

Possible malfunctions

The second point, which shows that the device is faulty and requires adjustment, is an increase in fuel consumption. There may be several reasons, so adjustment does not always help.

Carburetor adjustment K126G

If we approach the issue systematically, then it is necessary to distinguish the following types of carburetor settings:

idle move;
fuel level in the chamber with a float;
economizer valve.

Adjusting the K126G carburetor on a UAZ most often involves adjusting a specific idle speed. So, let's consider the sequence of actions to restore auto stability at idle.

Instructions for adjusting idling K126G

With the car turned off, tighten the mixture enrichment screw until it stops, and then unscrew it by 2.5 turns.
Start the car engine and warm it up.
With the first screw, achieve accurate and stable engine operation at about 600 rpm.
With the second screw (enrichment of the mixture), gradually deplete its composition so that the engine continues to work stably.
With the first screw we increase the number of revolutions by 100, and with the second we decrease them by the same amount.

The correctness of the adjustment is checked by increasing the speed to 1500 and then closing the throttle. In this case, the turnover should not fall below the permissible values.

Adjusting the fuel level in the float chamber

Variety of manufacturers

Among the manufacturers of the K126G carburetor there were:

"Solex";
"Weber";
"Pekar".

Advantages and disadvantages of K126G

The K126G carburetor is quite popular with UAZ owners. It is appreciated for a number of advantages that are not available in more modern models:

stable operation in the presence of clogging;
unpretentiousness to fuel quality;
sufficient savings.

The K126G carburetor, whose mixture quality is adjusted regularly, will work without any problems. Simplicity of a design - a guarantor of reliability. In this case, it will comply, but subject to scheduled maintenance.

K126G has one unpleasant drawback. In case of overheating, the body of the device may be deformed. This happens when the carburetor threaded connections are overtightened.

Conclusion

A.N.Tikhomirov

In this article you will find:

CARBURETORS K-126, K-135CAR GAS PAZ

Hello friends, 2 years ago, back in 2012, I ran into this wonderful book, even then I wanted to publish it, but as usual, there was no time, then my family, and now, today I stumbled upon it again and could not remain indifferent, after a little searching on the net, I realized that there are a lot of sites that offer to download it, but I decided to do it for you and publish it for self-development, read for health and gain knowledge.

Principle of operation, device, adjustment, repair

Publishing house "KOLESO" MOSCOW 2002

This brochure is intended for car owners, service station workers and people who study the structure of a car, and considers the theoretical foundations of carburation, design, features, possible methods for repairing and adjusting K-126 and K-135 carburetors of the Leningrad LENKARZ plant (now PECAR "), installed on cars of Gorky and buses of Pavlovsk Automobile Plants.

The brochure is intended for car owners, workshop workers and those who study the car

Cand. tech. Sciences A.N.Tikhomirov

From the author

K-126 series carburetors represent a whole generation of carburetors produced by the Leningrad carburetor plant "LENKARZ", which later became PECAR JSC (Petersburg carburetors), for almost forty years. They appeared in 1964 on the legendary GAZ-53 and GAZ-66 cars simultaneously with the then new ZMZ-53 engine. These engines, from the Zavolzhsky Motor Plant, replaced the famous GAZ-51, along with the single-chamber carburetor used on it.

A little later, since 1968, the Pavlovsk Bus Plant began producing PAZ-672 buses, in the seventies a modification of PAZ-3201 appeared, later PAZ-3205 and an engine made on the basis of the same one used on trucks, but with additional elements. The power system did not change, and the carburetor was also, respectively, of the K-126 family.

The impossibility of immediately completely switching to new engines led to the appearance in 1966 of the transitional car GAZ-52 with a six-cylinder engine. On them, in 1977, the single-chamber carburetor was also replaced by the K-126 with a corresponding replacement of the intake pipe. K-126I was installed on GAZ 52-03, and K-126E was installed on GAZ 52-04. The difference in carburetors concerns only different types of maximum speed limiters. Paired with carburetors K-126I, -E, -D, designed for the GAZ-52, a limiter was installed, which worked due to the high-speed pressure of air passing into the engine. The pneumocentrifugal limiter of the K-126B or K-135 carburetor on ZMZ engines operates on the signal of a centrifugal sensor mounted on the toe of the camshaft.

The ZMZ-53 engines were improved and changed. The last major change occurred in 1985, when the ZMZ-53-11 appeared with a full-flow oil filtration system, a single-stage intake pipe, screw intake ports, increased compression ratio and a K-135 carburetor. But the family has not been broken, the K-135 has all the body parts of the K-126 family and only some differences in the cross sections of the jets. In these carburetors, measures were taken to bring the composition of the prepared mixture to the requirements of the new time, and changes were made to more stringent toxicity standards. In general, the carburetor adjustments have shifted to a poorer side. The design of the carburetor took into account the introduction of an exhaust gas recirculation system (SROG) on engines by adding a vacuum extraction fitting to the SROG valve. In the text, we will not use the K-135 marking except for individual cases, considering it just one of the modifications of the K-126 series.
The natural difference between the engines on which the K-126 is installed is taken into account in the size of the dosing elements. First of all, these are jets, although diffusers of different diameters can also be found. Changes are reflected in the index assigned to each carburetor and this must be kept in mind when trying to replace one carburetor with another. A summary table of the dimensions of the main dosing elements of all modifications of the K-126 is given at the end of the book. The column "K-135" is valid for all modifications: K-135, K-135M, K-135MU, K-135X.

It should be remembered that the carburetor is only part of a complex complex called the engine. If, for example, the ignition system does not work properly, the compression in the cylinders is low, the intake tract is leaky, then it is at least illogical to blame the "failures" or high fuel consumption only on the carburetor. It is necessary to distinguish between defects related specifically to the power system, their characteristic manifestations during movement, and nodes that may be responsible for this. To understand the processes occurring in a carburetor, the beginning of the book is given to a description of the theory of regulation of spark ICEs and carburation.

Currently, Pavlovsk buses are practically the only consumers of eight-cylinder ZMZ engines. Accordingly, carburetors of the K-126 family are less and less common in the practice of repair services. At the same time, the operation of carburetors continues to ask questions that need answers. The last section of the book is devoted to identifying possible malfunctions of carburetors and how to eliminate them. Do not expect, however, that you will find a universal "master key" to eliminate every possible defect. Assess the situation for yourself, read what is said in the first section, "attach" it to your specific problem. Carry out a full range of work on adjusting the carburetor units. The book is intended primarily for ordinary drivers and those who maintain or repair power systems in bus or car fleets. I hope that after reading the book they will not have any more questions regarding this family of carburetors.

OPERATING PRINCIPLE AND CARBURETTOR DEVICE

1. Operating modes, ideal carburetor performance.

The power of internal combustion engines is determined by the energy that is contained in the fuel and released during combustion. To achieve more or less power, it is necessary, respectively, to supply more or less fuel to the engine. At the same time, an oxidizing agent, air, is necessary for the combustion of fuel. It is the air that is actually sucked in by the engine pistons during the intake strokes. With the “gas” pedal connected to the throttle valves of the carburetor, the driver can only limit the air supply to the engine or, on the contrary, allow the engine to fill up to the limit. The carburetor, in turn, must automatically monitor the flow of air entering the engine and supply a proportional amount of gasoline.

Thus, the throttle valves located at the outlet of the carburetor regulate the amount of the prepared mixture of air and fuel, and hence the engine load. Full load corresponds to the maximum throttle openings and is characterized by the highest flow of the combustible mixture into the cylinders. At "full" throttle, the engine develops the most power achievable at a given speed. For passenger cars, the share of full loads in real operation is small - about 10 ... 15%. For trucks, on the contrary, full load modes take up to 50% of the operating time. The opposite of full load is idling. In the case of a car, this is the operation of the engine with the gearbox disengaged, no matter what the engine speed is. All intermediate conditions (from idle to full loads) fall under the definition of partial loads.

A change in the amount of mixture passing through the carburetor also occurs at a constant throttle position in the event of a change in engine speed (the number of operating cycles per unit time). In general, the load and speed determine the mode of operation of the engine.

The car engine operates in a huge variety of operating modes caused by changing traffic conditions or the desire of the driver. Each mode of movement requires its own engine power, each mode of operation corresponds to a certain air flow and must correspond to a certain composition of the mixture. The composition of the mixture refers to the ratio between the amount of air and fuel entering the engine. Theoretically, the complete combustion of one kilogram of gasoline will occur if a little less than 15 kilograms of air is involved. This value is determined by the chemical reactions of combustion and depends on the composition of the fuel itself. However, in real conditions it turns out to be more profitable to maintain the composition of the mixture, although close to the named value, but with deviations in one direction or another. A mixture in which there is less fuel than theoretically necessary is called lean; in which more - rich. For quantitative assessment, it is customary to use the excess air coefficient a, showing the excess air in the mixture:

a \u003d Gv / Gt * 1o

where Gv is the air flow rate entering the engine cylinders, kg / h;

Gt is the consumption of fuel entering the engine cylinders, kg/h;

1o is the estimated amount of air in kilograms required

for burning 1 kg of fuel (14.5 ... 15).

For poor mixtures, a > 1, for rich mixtures, a< 1, смеси с а =1 называются стехиометрическими.

The main output parameters of the engine are the effective power Ne (kW) and the specific effective fuel consumption g = Gm/Ne (g/kWh). Specific consumption is a measure of efficiency, an indicator of the perfection of the engine's workflow (the smaller the value of ge, the higher the effective efficiency). Both parameters depend both on the quantity of the mixture and on its composition (quality).
What composition of the mixture is required for each mode can be determined by special adjustment characteristics taken from the engine on a brake stand at fixed throttle positions and constant speeds.
One of these characteristics is shown in Fig. 1.

Rice. 1. Adjustment characteristic according to the composition of the mixture: Engine ZMZ 53-18 n=2000 min’, P1,=68 kPa

The graph clearly shows that in this mode, the maximum power is achieved with an enriched mixture a = 0.93 (such a mixture is commonly called a power mixture), and the minimum specific fuel consumption, i.e. maximum efficiency, with poor a \u003d 1.13 (the mixture is called economical).

It can be concluded that the reasonable control limits lie in the interval between the points of power and economical adjustments (marked with an arrow in the figure). Outside these limits, the compositions of the combustible mixture are unfavorable, since working on them is accompanied by both a deterioration in efficiency and a drop in power. The increase in engine efficiency when the mixture is lean from power to economical is due to an increase in the completeness of fuel combustion. With further depletion of the mixture, the economy begins to deteriorate again due to a significant drop in power caused by a decrease in the combustion rate of the mixture. This should be remembered by those who, in the hope of reducing the fuel consumption of their engine, seek to limit the flow of gasoline into it.

For all partial load conditions, economical mixtures are preferred, and operating on economical mixtures will not limit us in power. It should be remembered that the power, which at a certain throttle position is achieved only with the power composition of the mixture, can also be obtained with an economical mixture, only with a slightly larger amount of it (with a larger throttle opening). The leaner the mixture we use, the more it will be required to achieve the same power. In practice, the power composition of the combustible mixture is organized only at full load.

Having taken a series of control characteristics at different throttle positions, it is possible to construct the so-called optimal control characteristics, showing how the composition of the mixture should change when the load changes (Fig. 2).

Rice. 2. Characteristics of the optimal regulation of the spark motor

In general, an ideal carburetor (if the focus is on economy rather than toxicity, for example) should change the composition of the mixture in accordance with the abc line. Each point on the section ab corresponds to the economical composition of the mixture for a given load. This is the longest part of the feature. At point b, a smooth transition to the enrichment of the mixture begins, continuing to point c.

Any amount of power could be achieved using only power mixtures over the entire characteristic (line dc). However, running those mixtures at partial loads doesn't make much sense, as there's room to get the same power by simply opening the throttle and letting in more of the still fuel-efficient mixture. Enrichment is really necessary only at full throttle openings, when the reserves for increasing the amount of the mixture are exhausted. If enrichment is not carried out, then the characteristic will “stop” at point b and the power gain ANt will not be achieved. We will get about 90% of the possible power.

2. Carburation, the formation of toxic components

In addition to dosing fuel, an important task facing the carburetor is the organization of mixing fuel with air. The fact is that combustion does not require liquid, but gasified, evaporated fuel. Directly in the carburetor, the first stage of mixture preparation takes place - atomization of the fuel, crushing it into as small drops as possible.

The higher the atomization quality, the more evenly the mixture is distributed over individual cylinders, the more homogeneous the mixture in each cylinder, the higher the flame propagation speed, power and efficiency while reducing the amount of products of incomplete combustion. The complete evaporation process does not have time to occur in the carburetor, and part of the fuel continues to move through the intake pipe to the cylinders in the form of a liquid film. The design of the intake pipe is thus of fundamental importance to the engine output. The heat necessary for the evaporation of the film is specially taken away and supplied to the air-fuel mixture from the coolant.

It should be remembered that the values of the optimal mixture compositions determined by the characteristics may vary depending on various factors. So, for example, they are all defined under the normal thermal state of the engine. The better the fuel is evaporated by the time it enters the cylinders, the leaner mixture compositions can achieve both maximum efficiency and maximum power. If the carburetor prepares an economical mixture for a warm engine, then at low temperatures (when warming up, with a faulty thermostat or its absence), this mixture will turn out to be poorer than necessary, the specific consumption will be sharply increased, and the operation will be unstable. The "colder" the engine, the richer the mixture must be supplied to it.

To a large extent, the composition of the air-fuel mixture determines the toxicity of exhaust gases. It should be remembered that an automobile internal combustion engine can never be completely harmless. As a result of fuel combustion, at the most favorable outcome, carbon dioxide CO2 and water H2O are formed. However, they are not toxic, i.e. poisonous, and do not cause any disease in humans.
Undesirable, first of all, not completely burned components of exhaust gases, the most important and most frequent components of which are carbon monoxide (CO), unburned or only partially burned hydrocarbons (CH), soot (C) and nitrogen oxides (NO "). All of them are toxic and dangerous to the human body. On fig. Figure 3 shows typical concentration curves of the three most known components as a function of mixture composition.

Rice. 3. Dependence of emissions of toxic components on the composition of the gasoline engine mixture

The concentration of carbon monoxide CO naturally increases with the enrichment of the mixture, which is explained by the lack of oxygen for the complete oxidation of carbon to CO2. An increase in the concentrations of unburned CH hydrocarbons in the region of rich mixtures is explained by the same reasons, and when depleted beyond a certain limit (dashed zone in the figure), a sharp rise in the CH curve is due to sluggish combustion and even misfires of such depleted mixtures that sometimes occur.

One of the most toxic components in exhaust gases are oxides of nitrogen, NOx. This symbol is assigned to a mixture of nitrogen oxides NO and NOa, which are not products of fuel combustion, but are formed in engine cylinders in the presence of free oxygen and high temperature. The maximum concentration of nitrogen oxides falls on the compositions of the mixture that are closest to economical ones, and the amount of emissions increases with increasing engine load. The danger of exposure to nitrogen oxides lies in the fact that the poisoning of the body does not appear immediately, and there are no neutralizing agents.
At idle modes, where the toxicity test familiar to all motorists is carried out, this component is not taken into account, since it is “cold” in the engine cylinders and NOx emissions in this mode are very small.

3. Main carburetor dosing system

K-126 carburetors are designed for multi-cylinder truck engines, which have a very large share of work at full loads. All cylinders in such engines, as a rule, are divided into groups, which are fed by separate carburetors or, as in the case of the K-126, by separate chambers of one carburetor. The division into groups is organized by manufacturing an inlet pipe with two independent groups of channels. Cylinders included in the same group are selected so that excessive air pulsations in the carburetor and distortion of mixture compositions.

For ZMZ eight-cylinder V-shaped engines, with the cylinder operation order adopted for them, a uniform alternation of cycles in two groups will be observed when the cylinders operate through one (Fig. 4 A). From fig. 4B it can be seen that with such a division, the channels in the intake pipe must intersect, i.e. be performed at different levels. It was so on the ZMZ-53 engine: the intake pipe was two-tiered.

Rice. 4. Scheme of division of eight-cylinder engines

into groups with uniform alternation:

a) in order of work; b) by location on the engine.

On ZMZ 53-11 engines, among other changes, they simplified the casting of the intake pipe, making it single-tier. From now on, the channels in the groups do not intersect, the cylinders of the left half-block belong to one group, and the right half-block to the second (Fig. 5).

Rice. 5. Scheme of dividing eight-cylinder engines into groups with a single-tier intake pipe:

a) in order of work; b) by location on the engine.

1 - the first chamber of the carburetor, 2 - the second chamber of the carburetor

The cheaper design had a negative impact on the working conditions of the carburetor. The uniformity of the alternation of cycles in each of the groups was violated, and with it the uniformity of the air intake pulses in the carburetor chambers. The engine becomes prone to mixture dispersion in individual cylinders and successive cycles. At some average value, which is prepared by the carburetor, in individual cylinders (or cycles of the same cylinder), the mixture can be either richer or leaner. Therefore, if the average composition of the mixture deviates from the optimum in some cylinders, the mixture is more likely to go beyond the ignition limits (cylinder turns off). It is possible to smooth over the created situation partly due to the presence of a film of unevaporated fuel in the intake pipe, which "creeps" to the cylinders relatively slowly.

Despite all the above features, the K-126 vertical carburetor, with a falling stream, with parallel opening of the throttles, is actually two identical carburetors assembled in one housing, where a common float chamber is located for them. Accordingly, it has two main dosing systems operating in parallel. On fig. 6 shows a diagram of one of them. It has a main air channel, which includes a small diffuser (atomizer) 16, installed in a narrow section of the main large diffuser 15, and a mixing chamber with a throttle 14. The throttle is a plate mounted on an axis, turning which you can adjust the flow area of the mixing chamber and hence the air flow. Parallel opening of the throttles means that in each mixing chamber the throttle valves are installed on a common axle, the drive of which is organized from the “gas” pedal. By acting on the pedal, we open both throttles to the same angle, which ensures equality of air passing through the carburetor chambers.

The main metering system performs the main task of the carburetor - metering fuel in proportion to the air entering the engine. It is based on a diffuser, which is a local narrowing of the main channel. In it, due to the relative increase in air velocity, a rarefaction (pressure below atmospheric pressure) is created, depending on the air flow. The vacuum formed in the diffusers is transmitted to the main fuel jet 11 located at the bottom of the float chamber.

Rice. 6. Scheme of the main dosing system of the K-126 carburetor: 1 - air inlet pipe; 2 - fuel filter plug; 3 - float chamber cover; 4 - fuel filter; 5 - fuel input from the fuel pump; 6 - float chamber valve; 7 - body of the float chamber; 8 - float; 9 - needle of the float chamber valve; 10 - plug of the main fuel jet; 11 - main fuel jet; 12 - main air jet; 13 - emulsion tube; 14 - throttle valve; 15 - large diffuser; 16 - small diffuser; 17 - economizer sprayer; 18 - spray accelerator pump; 19 - air inlet

They are accessed through threaded plugs 10 screwed into the wall of the body of the float chamber 7. Any calibrated hole for dosing fuel, air or emulsion is called a jet. The most critical of them are made in the form of separate parts inserted into the housing on the thread (Fig. 7). For any jet, not only the flow area of the calibrated part is fundamental, but also the ratio between the length and diameter of the calibrated part, the angles of the input and output chamfers, the quality of the edges and even the diameters of the non-calibrated parts.

The required proportion of fuel with air is provided by the ratio of the cross-sectional area of the fuel jet and the cross-section of the diffuser. An increase in the jet will lead to an enrichment of the mixture in the entire range of modes. The same effect can be achieved by reducing the flow area of the diffuser. The sections of the carburetor diffusers are selected based on two conflicting requirements: the larger the area of the diffusers, the higher the power can be achieved by the engine, and the worse the quality of fuel atomization due to lower air velocities.

Rice. 7. Scheme of the fuel jet

l is the length of the calibrated part

Given that large diffusers are plug-in and unified in size for all modifications of K-126 (including cars), do not make a mistake when assembling. A diffuser with a diameter of 24 mm can easily be installed in place of a regular one with a diameter of 27 mm.
To further improve the quality of atomization, a scheme with two diffusers (large and small) was used. Small diffusers are separate parts inserted in the middle of the large ones. Each of them has its own atomizer connected by a channel to an opening in the housing from which fuel is supplied.

Be careful about channel orientation!

Each jet is stamped with a number showing the capacity in cm3/min. This marking is accepted on all PECAR carburetors. The check is carried out on a specialized pouring device and means the amount of water in cm3 passing through the jet in the forward direction per minute at a liquid column pressure of 1000 ± 2 mm. Deviations in the throughput of jets from the normative ones should not exceed 1.5%.

Only a specialized company with the appropriate equipment can truly make a jet. Unfortunately, many people take up the production of repair jets, and as a result, one cannot be completely sure that the main fuel jet marked "310" will not actually be the size "285". From experience it is better to never change factory jets, especially since there is no special need for this. The jets do not wear out noticeably even during long-term operation, and a decrease in cross-section due to resins deposited on the calibrated part is unlikely with modern gasolines.

In the carburetor, for the stability of the pressure drop across the fuel jet, the fuel level in the float chamber must remain constant. Ideally, the fuel should be at the level of the atomizer lip. However, in order to prevent spontaneous outflow of gasoline from the atomizer, with possible vehicle tilts, the level is maintained 2 ... 8 mm lower. In most modes of operation (especially a truck, which has a large proportion of full loads), such a decrease in the level cannot have any noticeable effect on the flow of gasoline. The rarefaction in the diffuser can reach a value of 10 kPa (which corresponds to 1300 mm of the "gasoline" column) and, of course, lowering the level by a few millimeters does not change anything. It can be assumed that the composition of the mixture prepared by the carburetor is determined only by the ratio of the areas of the fuel jet and the narrow section of the diffuser. Only at the lowest loads, when the rarefaction in the diffusers falls below 1 kPa, errors in the fuel level begin to have an effect. To eliminate fluctuations in the fuel level in the float chamber, a float mechanism is installed in it. It is assembled entirely on the carburetor cover, and the fuel level is automatically adjusted by changing the bore section of valve 6 (Fig. 8) with valve needle 5, actuated by tongue 4 on the float holder.

Rice. 8. Carburetor float mechanism:

1 - float; 2 - float stroke limiter; 3 - axis of the float; 4 - level adjustment tab; 5 - valve needle; 6 - valve body; 7 - sealing washer; A is the distance from the plane of the cover connector to the upper point of the float; B - gap between the end of the needle and the tongue

As soon as the fuel level drops below the predetermined level, the float lowers the tongue, lowering with it, which will allow the needle 5, under the influence of the fuel pressure created by the fuel pump, and its own weight to lower and let more gasoline into the chamber. It can be seen that the fuel pressure plays a certain role in the operation of the float chamber. Almost all gasoline pumps must create a gasoline pressure of 15 ... 30 kPa. Deviations to a large side can, even with the correct adjustments of the float mechanism, create fuel leakage through the needle.

To control the fuel level in earlier modifications of the K-126, there was a viewing window on the wall of the float chamber housing. Along the edges of the window, approximately along its diameter, there were two tides that marked the line of normal fuel level. In the latest modifications, there is no window, and the normal level is marked with a mark 3 (Fig. 9) on the outside of the case.

Rice. 9. View of the carburetor from the side of the fittings: 1 - channel into the supra-membrane limiter; 2 - plugs of the main fuel jets; 3 - risk of fuel level in the float chamber; 4 - supply channel from the fuel pump; 5 - thrust; 6 - vacuum extraction fitting to the recirculation valve; 7 - channel submembrane restrictor chamber

To increase the reliability of locking, a small polyurethane washer 7 is put on the valve needle 5 (Fig. 8), which retains elasticity in gasoline and reduces the locking force several times. In addition, due to its deformation, float fluctuations that inevitably occur when the car is moving are smoothed out. When the washer is destroyed, the tightness of the assembly is immediately irreversibly violated.

The float itself can be brass or plastic. The reliability (tightness) of both is quite high, unless you yourself deform it. To prevent the float from knocking on the bottom of the float chamber in the absence of gasoline in it (which is most likely when dual-fuel gas-balloon vehicles are operating), there is a second antennae 2 on the float holder, which rests on a rack in the housing. By bending it, the stroke of the needle is regulated, which should be 1.2 ... 1.5 mm. On a plastic float, this antennae is also plastic, i.e. you can't bend it. Needle stroke is not adjustable.

An elementary carburetor, having only a diffuser, an atomizer, a float chamber and a fuel jet, is able to maintain the composition of the mixture approximately constant throughout the entire region of air flow (except for the smallest ones). But in order to get as close as possible to the ideal dosing characteristic, the mixture should be leaner with increasing load (see Fig. 2, section ab). This problem is solved by introducing a mixture compensation system with pneumatic fuel braking. It includes an emulsion well installed between the fuel jet and the atomizer with an emulsion tube 13 and an air jet 12 placed in it (see Fig. 6).

The emulsion tube is a brass tube with a closed lower end, having four holes at a certain height. It descends into the emulsion well and is pressed from above with an air jet screwed on the thread. With an increase in load (vacuum in the emulsion well), the fuel level inside the emulsion tube drops and, at a certain value, is below the holes. Air begins to flow into the atomizer channel, passing through the air jet and holes in the emulsion tube. This air mixes with the fuel before it exits the atomizer, forming an emulsion (hence the name), facilitating further atomization in the diffuser. But the main thing is that the supply of additional air lowers the level of vacuums transmitted to the fuel jet, thereby preventing excessive enrichment of the mixture and giving the characteristic the necessary “slope”. Changing the cross section of the air jet will have practically no effect at low engine loads. At high loads (high air flow rates), an increase in the air jet will provide a greater depletion of the mixture, and a decrease - enrichment.

4. Idling system

At low air flow rates, which are available at idle, the vacuum in the diffusers is very small. This leads to instability of fuel metering and a high dependence of its consumption on external factors, such as fuel level. Under the throttle valves in the intake pipe, on the contrary, it is in this mode that the vacuum is high. Therefore, at idle and at small throttle opening angles, the fuel supply to the atomizer is replaced by the supply under the throttle valves. For this, the carburetor is equipped with a special idle system (CXX).

On K-126 carburetors, the CXX scheme with throttle spraying is used. The air into the engine at idle passes through a narrow annular gap between the walls of the mixing chambers and the edges of the throttle valves. The degree of closure of the throttles and the cross section of the slots formed is regulated by the stop screw 1 (Fig. 10). Screw 1 is called the "quantity" screw. By turning it in or out, we regulate the amount of air entering the engine, and thereby change the engine idling speed.

The throttle valves in both chambers of the carburetor are installed on the same axis and the “quantity” stop screw adjusts the position of both throttles. However, the inevitable errors in the installation of throttle plates on the axis lead to the fact that the flow area around the throttles can be different. At large opening angles, these differences are not noticeable against the background of large flow sections. At idle, on the contrary, the slightest differences in the installation of throttles become fundamental. The inequality of the flow sections of the carburetor chambers causes different air flow through them. Therefore, in carburetors with parallel opening of throttles, one screw for adjusting the quality of the mixture cannot be installed. Personal adjustment by cameras is required with two “quality” screws.

Rice. 10. Carburetor adjusting screws:

1 - throttle stop screw (quantity screw); 2 - mixture composition screws (quality screws); 3 - restrictive caps

In the family under consideration, there is one K-135X carburetor, in which the idle system was common to both chambers. There was only one “quality” adjusting screw and was installed in the center of the mixing chamber body. From it, fuel was supplied to a wide channel, from which it diverged into both chambers. This was done to organize the EPHH system, the forced idle economizer. The solenoid valve blocked the common idle channel and was controlled by the electronic unit according to signals from the ignition distributor sensor (speed signal) and from the limit switch installed at the "quantity" screw. The modified screw with the platform is visible in fig. 14. Otherwise, the carburetor does not differ from the K-135.

The K-135X is an exception and, as a rule, carburetors have two independent idle systems in each carburetor chamber. One of them is schematically shown in Fig. 11. The selection of fuel in them is made from the emulsion well 3 of the main metering system after the main fuel jet 2. From here, the fuel is supplied to the idle fuel jet 9, screwed vertically into the body of the float chamber through the cover so that it can be turned out without disassembling the carburetor. The calibrated part of the jets is made on the toe, below the sealing belt, which abuts against the body when screwed. If there is no tight contact of the belt, the resulting gap will act as a parallel jet with a corresponding increase in cross section. On older carburetors, the idle fuel jet had an elongated nose that dropped to the bottom of its well.

After exiting the fuel jet, the fuel meets the air supplied through the idle air jet 7, screwed under the plug 8. engine.
The mixture of fuel and air forms an emulsion, which descends through channel 6 down to the throttle body. Further, the flow is divided: part goes to the transition hole 5 just above the throttle edge, and the second part goes to the “quality” adjusting screw 4. After adjusting the screw, the emulsion is discharged directly into the mixing chamber after the throttle valve.

On the carburetor body, the “quality” screws 2 (Fig. 10) are located symmetrically in the throttle body in special niches. To prevent the owner from violating the adjustments, the screws can be sealed. To do this, they can be put on plastic caps 3, which limit the rotation of the adjusting screws.

Rice. 11. Scheme of the idle system and the transition system: 1 - float chamber with a float mechanism; 2 - main fuel jet; 3 - emulsion well with an emulsion tube; 4 - screw "quality"; 5 - via; 6 - fuel supply channel to the openings of the idle system; 7 - idle air jet; 8 - air jet plug; 9 - idle fuel jet; 10 - inlet air pipe

5. Transition systems

If the throttle of the primary chamber is smoothly opened, then the amount of air passing through the main diffuser will increase, but the vacuum in it will still not be enough for the fuel to flow out of the atomizer for some time. The amount of fuel supplied through the idle system will remain unchanged, since it is determined by the vacuum behind the throttle. As a result, the mixture will begin to become leaner during the transition from idling to the operation of the main dosing system, up to the engine shutdown. To eliminate the “failure”, transitional systems are organized that operate at small throttle opening angles. They are based on vias located above the upper edge of each throttle when they are positioned against the “quantity” screw. They act as additional variable-section air jets that control the vacuum at the idle fuel jets. At minimum idle speed, the via is located above the throttle in an area where there is no vacuum. There is no leakage of gasoline through it. When moving the throttle up, the holes are first blocked due to the thickness of the damper, and then they fall into the zone of high throttle vacuum. High vacuum is transmitted to the fuel jet and increases fuel flow through it. The outflow of gasoline begins not only through the outlet holes after the “quality” screws, but also from the through holes in each chamber.

The cross section and location of the vias are chosen so that with a smooth opening of the throttle, the composition of the mixture should remain approximately constant. However, to solve this problem, one via, which is available on K-126, is not enough. Its presence only helps to smooth out the “failure” without completely eliminating it. This is especially noticeable on the K-135, where the idle system is made poorer. In addition, the operation of the transitional systems in each of the chambers is affected by the identical installation of the throttle plates on the axle. If one of the throttles is higher than the second, then it begins to block the via earlier. In the other chamber, and hence in the group of cylinders, the mixture may remain poor. Again, the fact that for a truck the operating time at light loads is short helps to smooth out the poor quality of the transitional systems. Drivers “step over” this mode by opening the throttle immediately to a large angle. To a large extent, the quality of the transition to the load depends on the operation of the accelerator pump.

6. Economizer

The economizer is a device for supplying additional fuel (enrichment) at full load. Enrichment is necessary only at full throttle openings, when the reserves for increasing the amount of the mixture have been exhausted (see Fig. 2, section bc). If enrichment k is carried out, then the characteristic will “stop” at point b and the increase in power ANe will not be achieved. We will get about 90% of the possible power.

In the K-126 carburetor, one economizer serves both carburetor chambers. On fig. 12 shows only one camera and its related channels.
The economizer valve 12 is screwed into the bottom of a special niche in the float chamber. Above it is always gasoline. In the normal position, the valve is closed, and in order to open it, a special rod 13 must press on it. The rod is fixed on a common bar 1 together with the piston of the accelerator pump 2. With the help of a spring on the guide rod, the bar is held in the upper position. The bar is moved by a drive lever 3 with a roller, which is rotated by a rod 4 from the throttle drive lever 10. The drive adjustments should ensure that the economizer valve is activated when the throttles are opened by about 80%.

From the economizer valve, fuel is supplied through channel 9 in the carburetor body to the atomizer unit. The K-126 atomizer block combines two atomizers of the economizer 6 and the accelerator pump 5 (for each carburetor chamber). The atomizers are located above the fuel level in the float chamber and for the expiration through them, gasoline must rise to a certain height. This is possible only in modes where the spray nozzles have a rarefaction. As a result, the economizer supplies gasoline only when the throttles are fully opened and the speed is increased, i.e. partly performs the functions of an econostat.
The higher the rotational speed, the greater the vacuum created at the atomizers, and the more fuel is supplied by the economizer.

Rice. 12. Scheme of economizer and accelerator pump:

1 - drive bar; 2 - accelerator pump piston; 3 - drive lever with a roller; 4 - thrust; 5 - spray accelerator pump; 6 - economizer sprayer; 7 - discharge valve; 8 - fuel supply channel of the accelerator pump; 9 — economizer fuel supply drip; 10 - throttle lever; 11 - inlet valve; 12 - economizer valve; 13 — economizer push rod; 14 - guide rod

7. Accelerator pump

All the systems described above ensure the operation of the engine in stationary conditions, when the operating modes do not change, or change smoothly. With sharp pressure on the "gas" pedal, the conditions for supplying fuel are completely different. The fact is that the fuel enters the engine cylinders only partially evaporated. Some of it moves along the intake pipe in the form of a liquid film, evaporating from the heat supplied to the intake pipe from the coolant circulating in a special shirt at the bottom of the intake pipe. The film moves slowly and the final evaporation can occur already in the engine cylinders. With a sharp change in throttle position, the air almost instantly takes on a new state and reaches the cylinders, which cannot be said about fuel. That part of it, which is enclosed in a film, cannot also quickly reach the cylinders, which causes some delay - a “failure” when the throttles are suddenly opened. It is aggravated by the fact that when the throttles are opened, the vacuum in the intake pipe drops, and at the same time, the conditions for gasoline evaporation worsen.

To eliminate the unpleasant “failure” during acceleration, so-called accelerator pumps are installed on carburetors - devices that supply additional fuel only with sharp throttle openings. Of course, it will also turn into a fuel film in many respects, but due to a larger amount of gasoline, the “failure” can be smoothed out.

On K-126 carburetors, a mechanical piston-type accelerator pump is used, which supplies fuel to both chambers of the carburetor, regardless of the air flow (Fig. 12). It has a piston 2, moving in the discharge chamber, and two valves - inlet 11 and discharge 7, located in front of the atomizer block. The piston is fixed on a common bar 1 together with the economizer push rod. The piston moves up during the suction stroke (when the throttle is closed) under the action of a return spring, and when the throttle is opened, the bar with the piston goes down under the action of lever 3, driven by rod 4 from throttle lever 10. In the first K-126 designs, the piston did not have a special seal and had inevitable leaks during operation. The modern piston has a rubber sealing cuff that completely insulates the discharge cavity.

On the course of suction, under the action of a spring, piston 2 rises and increases the volume of the discharge cavity. Gasoline from the float chamber through the inlet valve 11 passes freely into the discharge chamber. The discharge valve 7 in front of the atomizer closes and does not let air into the injection chamber.

With a sharp turn of the throttle drive lever 10, the rod 4 turns on the axis the lever 3 with the roller, which presses the bar 1 with the piston 2. Since the piston is connected to the bar through the spring, in the first moments the diaphragm does not move, but only the spring is compressed under the bar, since gasoline filling the chamber cannot leave it quickly. Further, the already compressed piston spring begins to squeeze out gasoline from the discharge chamber to the sprayer 5. The discharge valve does not prevent this, and the inlet valve 11 blocks the possible leakage of fuel back into the float chamber.
The injection is thus determined by the piston spring, which must, at a minimum, overcome the friction of the piston and its cuff against the walls of the injection chamber. After deducting this force, the spring determines the injection pressure and implements continued fuel injection for 1 ... 2 seconds. The injection ends when the piston is lowered to the bottom of the injection chamber. Further movement of the bar only compresses the spring.

8. Launcher

No matter how well the listed carburetor systems are configured, its operation cannot be considered complete if measures are not taken to ensure the proper composition of the mixture when starting a cold engine and warming it up. The peculiarity of a cold start is that the resistance to turning the crankshaft due to thick oil is high, the engine turns at a low speed, the vacuum in the intake system is small, and there is practically no evaporation of gasoline.
For a reliable cold start in conditions of poor fuel volatility, the creation of the required mixture composition is possible only by multiplying the amount of gasoline supplied to the engine.
A significant part of it still will not evaporate, but a larger amount of gasoline will produce a larger amount of vapors, which, mixed with air, will organize a mixture that can ignite.

The creation of an extremely rich mixture during a cold start is carried out using an air damper 7 installed in the air channel above the diffusers 5 (Fig. 13). The air damper is fully closed in the cocked position. Air is forced to pass into the engine through two air valves 6, overcoming the resistance of the springs. As a result, an increased vacuum is formed under the damper, disproportionate to the actual air flow through the carburetor. The amount of air practically does not change, but at the nozzle outlet of the main dosing system, an increased vacuum causes an increased outflow of gasoline. The greater the force of the springs of the air valves, the higher the vacuum and the greater the enrichment created in the start-up mode.

However, enrichment of the mixture alone is not enough for a reliable start-up. In order for a cold engine to run independently, the amount of rich mixture supplied must also be increased. Otherwise, the work done in the engine cylinders will be insufficient to overcome the increased resistance to cranking of all engine mechanisms.

Rice. 13. Scheme of the starting device for the K-126 carburetor: 1 - float mechanism; 2 - main fuel jet; 3 - emulsion well; 4 - throttle body; 5 - diffusers of the main dosing system; 6 - air valve; 7 - air damper; A - throttle opening

To increase the amount of mixture on the cocked trigger mechanism, in addition to closing the air damper, simultaneous opening of the throttle valves is provided. The amount of throttle opening A determines the amount of mixture supplied to the engine.

Rice. 14. Adjusting the opening angle of the throttle valves when closed

air damper (cold start):

1 - throttle lever; 2 - thrust; 3 - adjusting bar; 4 - accelerator pump drive lever; 5 - air damper drive lever; 6-axis air damper

Two main elements - an air damper and a slightly opener - make it possible to provide the first stage of a cold start, i.e. the start itself and the first few revolutions of the motor shaft. After the speed has increased by more than 1000 min "', the vacuum in the intake system increases sharply, a high temperature is created in the engine cylinders and the mixture supplied by the starting device becomes too rich.

If steps are not taken to reduce enrichment, the engine will most likely stop after a few seconds. The driver must remove the excessive enrichment by sinking the starter drive button (the “choke” button). The air damper opens slightly and the air begins to pass not only through the air valves, but also around. At the same time, there is a decrease in the slightly open throttles and a corresponding decrease in the supply of the combustible mixture and speed. The regulation of the mixture in the warm-up mode is completely entrusted to the driver, who must sensitively adjust the position of the "suction" handle in order to prevent both excessive enrichment and excessive depletion of the mixture.

All control of the starting device is carried out from one lever of the air damper drive 5 (Fig. 14). The driver, pulling out the starter drive handle in the cabin, turns lever 5 counterclockwise, and thereby cocks the entire starter mechanism. The axis of the air damper 6, connected with the lever 5, rotates and closes it. One shoulder on the lever 5, when turning, slides along the adjusting bar 3 and. turns the lever 4 of the accelerator pump drive at a certain angle. At the same time, the thrust 2 opens the throttle valves through the lever 1, increasing the flow area for the mixture. The amount of throttle opening is regulated by moving the adjusting bar 3. To increase the opening, the bar should be moved towards the lever 5.

9. Engine speed limiter

K-126 carburetors are designed for truck engines with increased load conditions. This is not a whim of drivers, just in order to move, accelerate, lift such a heavy car uphill, more power is needed. With an increase in revolutions, the engine power naturally increases, but the wear of the parts of the cylinder-piston group also naturally increases. To prevent increased wear, truck engines are usually limited by the crankshaft speed. Regulation is carried out by changing the flow area of the intake tract, and can be carried out in two ways: with the help of special regulator valves, or by the carburetor throttle valves themselves.

The design of the limiter includes a special stabilizing device that prevents the opening of the regulator damper.
Separate limiters for the maximum speed of engines with a K-126I, -E carburetor are used on six-cylinder GAZ-52 engines. The limiter is available as a separate spacer, which is mounted between the carburetor and the engine intake pipe (Fig. 15). Under the K-126, the limiter has two chambers, coinciding with the chambers of the carburetor. In each of them, the main parts are a damper and a spring. The dampers are installed eccentrically to the carburetor centerline and at a certain initial angle.

When the engine is running, the dampers of the regulator are affected by the velocity pressure of the combustible mixture and the vacuum present in the throttle cavity. The total moment of forces acting on the dampers will tend to close them. This closing is counteracted by the spring of the limiter 14. Rotation of the flaps towards the cover can only occur if the total moment of forces acting on the flaps increases and becomes greater than the moment of the spring. In order for the flaps to close relatively smoothly, the spring force application arm is made variable.

Rice. 15. Pneumatic speed limiter: 1 - piston; 2 - stock; 3 - roller; 4 - bracket; 5 - axis; 6 - dampers of the regulator; 7 - screw; 8 - nut; 9 - felt filter; 10 - spring clamp; 11 - cam; 12 - body; 13 - tape traction; 14 - limiter spring with the carburetor throttle covered.

With the carburetor throttle closed. The device consists of a rod 2, a piston 1 and a well, the rod is connected to the regulator throttle. Air enters the well through a felt filter 9, fixed in the housing with a washer and a spring clamp 10. If, with the carburetor throttle valves closed, large vacuums occur above the regulator damper, then it will also be covered, at partial loads without "casts".

The K-126 carburetor for eight-cylinder engines has a built-in pneumatic centrifugal maximum speed limiter. This limiter consists of two main units: a command pneumocentrifugal sensor and a membrane actuator (Fig. 16)

The pneumocentrifugal sensor consists of a stator housing and a rotor 3 located inside. The sensor is mounted on the cover of the engine timing mechanism, and the rotor is rigidly connected to the camshaft. The valve mechanism of the rotor is located perpendicular to the axis of rotation. Valve 4 simultaneously plays the role of a centrifugal regulator weight. The internal cavity of the rotor communicates with one output of the sensor, and the cavity of the housing - with another. The message of the two formed chambers occurs only through the valve seat when it is in its open position. mechanism 1 is fastened with three screws to the body of the carburetor mixing chambers. It consists of a membrane with a rod 2, a two-arm lever 8 and a spring 7.
The two-arm lever is fixed with a nut on the axis of the throttle valves 11. The spring, engaged on one lever arm, is put on the pin fixed in the actuator housing with the second end. To adjust the spring preload, the pin can be installed in any of the four sockets provided in the body. The membrane rod is hooked to the other arm of the lever. The cavities inside the actuator under and above the membrane have outlets that are connected by copper tubes 6 to the corresponding outlets on the centrifugal sensor.

Rice. Fig. 16. Scheme of the pneumocentrifugal limiter of the frequency: 1 - the actuator of the limiter; 2 - membrane with a rod; 3 - centrifugal sensor rotor; 4 - valve; 5 — sensor adjustment screw; 6 - connecting tubes; 7 - limiter spring; 8 - two-arm lever; 9 - channel into the submembrane cavity; 10 - jets in the channels of the supra-membrane cavity; 11 - throttle axis; 12 - vacuum supply channel; 13 - fork connection; 14 - throttle drive lever

The carburetor's throttle valve axle is mounted in roller bearings to reduce friction and enable rotation by a relatively weak membrane mechanism. To seal the cavity of the actuator, the axis of the throttle valves is sealed with a rubber gland pressed against the walls of the chamber by a spacer spring. At the second end of the axle is the throttle drive lever 14, mounted on its short axle. The connection of the drive axis with the axis of the forked type chokes 13 is made so that under the action of the membrane mechanism of the limiter, the chokes can be closed regardless of the position of the drive lever.

Thus, the name "drive lever" is conditional. It does not actually open the throttles (nor does the person pressing the drive pedal), but only gives "permission" to the throttles to open. The actual opening of the carburetor throttles is carried out by a spring in the actuator housing, provided that the regulator has not yet entered into operation (the rotational speed has not reached the limit value).

The cavity above the membrane is connected by a channel simultaneously with the space under and above the throttle valves through two jets 10. Through them there is a constant overflow of air from the space above the throttle into the throttle space. The resulting vacuum entering the above membrane cavity is, as a result, lower than the purely throttle vacuum, but sufficient to overcome the spring force and move the membrane upward. The cavity of the actuator under the membrane channel 9 communicates with the intake neck of the carburetor. The centrifugal sensor is connected to the diaphragm actuator in parallel.

At frequencies below the threshold (3200 min»1), the valve in the sensor rotor is pulled away from the seat by a spring. Through the hole in the seat, the outputs from the sensor communicate with each other and shunt the supra- and submembrane cavities. The vacuum coming from under the throttle through channel 12 is extinguished by air coming from the carburetor neck through a centrifugal sensor. The membrane is not able to overpower the spring that opens the throttle. When the maximum speed is reached, the centrifugal forces acting on valve 4 overcome the force of the spring and press the valve against the seat. The outputs of the centrifugal sensor are disconnected, and the membrane chamber remains under the action of a different vacuum on both sides of the membrane. The membrane, together with the rod, moves upward and closes the throttles, despite the fact that the driver continues to press or keep the drive lever 14 pressed.

CARBURETTOR MAINTENANCE AND ADJUSTMENT

The creation of a reliable design is ensured, on the one hand, by designers who lay down solutions with high operational reliability and maintainability, and on the other hand, by the competent operation of devices to maintain the proper technical condition. K-126 carburetors are very simple in design, moderately reliable and require minimal maintenance with proper operation.

Most malfunctions occur either after unskilled intervention in the adjustments or in the event of clogging of the dosing elements with solid particles. Among the types of maintenance, the most common are flushing, adjusting the fuel level in the float chamber, checking the operation of the accelerator pump, adjusting the start-up system and the idle system.
Another service option is when intervention in the carburetor occurs only after a clear malfunction has been detected. In other words, repair. In this case, only those nodes that are previously identified as the most likely culprits of malfunctions can be disassembled.

For maintenance and adjustment of the carburetor, it is not always necessary to remove it from the engine. By removing the air filter housing, it is already possible to provide access to many carburetor devices. If you still decide to carry out a complete maintenance of your carburetor, then it is better to do this by removing it from the car.

Dismantling the carburetor

After the air filter housing is removed, it begins with disconnecting the gasoline supply hose from the carburetor, the vacuum extraction tubes for the vacuum ignition timing regulator and the recirculation valve (if any), two copper tubes from the limiter and the air damper control rod. The rod is fastened with two screws: one on the bracket secures the braid, and the second on the air damper actuator lever secures the rod itself. To disconnect the throttle actuator linkage, it is more expedient to unscrew the nut on the throttle control lever, which fastens the rack with a spherical head from the inside.

The rack will be removed from the lever and remain on the rod coming from the driver's pedal. Then it remains to unscrew the four nuts securing the carburetor to the intake pipe, remove the washers so that they do not accidentally fall inward, and remove the carburetor from the studs. It is necessary to separate the gasket under it so that it does not stick, but remains on the intake pipe. Next, you can set the carburetor aside and be sure to securely plug the holes on the intake pipe with some rag. This operation will not take much time, but will prevent many troubles associated with getting something (for example, nuts) inside the engine.

Flushing the carburetor

Although K-126, like all carburetors, is demanding on cleanliness, frequent flushing should not be abused. When disassembling, it is easy to bring dirt into the carburetor or break worn-in connections or seals. External washing is done with a brush using any liquid that dissolves oily deposits. It can be gasoline, kerosene, diesel fuel, their analogues or special flushing fluids that are soluble in water. The latter are preferable because they are not so aggressive to human skin and are not flammable. After washing, you can blow air over the carburetor, or simply blot lightly with a clean cloth to dry the surface. As already mentioned, the need for this operation is small, and it is not necessary to wash only for the sake of shine on the surfaces. To flush the internal cavities of the carburetor, you will need to at least remove the float chamber cover.

Removing the top cover

you need to start by disconnecting the economizer drive rod and the accelerator pump. To do this, unpin and remove the upper end of the link 2 from the hole in the lever (see Fig. 14). Then, unscrew the seven screws securing the float chamber cover, and remove the cover without damaging the gasket. To make it easier to remove the cover, press the choke lever with your finger until it is in a vertical position. At the same time, it turns out to be opposite the recess in the body and does not cling to it. Take the cover aside and only then turn it over the table so that the screws fall out (if you did not remove them immediately). Evaluate the quality of the impression and the general condition of the gasket. It should not be torn and a clear imprint of the body should be traced around the perimeter.

Warning: Do not put the carburetor cap on the table with the float down!

Cleaning the float chamber

It is carried out in order to remove the sediment that forms at its bottom. With the cover removed, remove the bar with the accelerator pump piston and the economizer drive and remove the spring from the guide. Next, rinse and scrape off those deposits that are easily fed. Dirt that has stuck firmly to the walls is not dangerous - let it remain. Otherwise, with careless work, debris may begin to float inside. The probability of clogging of channels or jets with improper cleaning is much greater than during normal operation.

There is only one source of debris in the float chamber - gasoline. Most likely, the fuel filter does not work on the engine (that is, it formally stands, but does not filter anything). Check the status of all filters. In addition to the fine filter, which is mounted on the engine and has a mesh, paper or ceramic filter element inside, there is another one on the carburetor itself. It is located under plug 1 (Fig. 17) near the gasoline supply fitting on the carburetor cover.

Filter Care

It consists in cleaning the sump from dirt, water and sediment and replacing paper filter elements. Mesh filter elements should be washed, and ceramic ones can be burned out by heating them until the gasoline accumulated in the pores ignites spontaneously. Of course, this must be done with all precautions. After cooling slowly, the ceramic filter element can be reused many times.

Checking the condition of the jets

Under the float at the bottom of the float chamber are two main fuel jets. Unscrew two plugs 10 (Fig. 17) outside the body of the float chamber and unscrew the fuel jets of the main dosing system. Check through their channels for cleanliness and read the markings embossed on each of them. The marking must match the brand of the carburetor.

Rice. 17. View of the carburetor from the drive side:
1 - fuel filter plug; 2 - adjusting strip of the opener;
3 - accelerator pump drive lever; 4 - axis of the air damper;
5 - air damper drive lever; 6 - thrust; 7 - screw "quantity";
8 - throttle drive lever; 9 — the union of selection of rarefaction on the valve
recycling; 10 - plugs of the main fuel jets

Two air jets of the main dosing system 6 are visible on the upper plane of the housing connector (Fig. 18). Air jets are more likely to become clogged than fuel jets because they are subject to "direct hit" by particles flying from above with the air. The reason may be imperfect air purification.

Traditionally, an inertia-oil air filter was installed on engines with K-126. The degree of air purification in them reaches 98% with proper assembly and timely maintenance (changing the oil in the filter housing, washing the muddle). But if a gasket is not placed between the filter housing and the carburetor, or it is squeezed out to the side when tightened, then a gap is formed for uncleaned air through which it can enter the engine.

Relatively recently, air filters with a paper filter element began to be installed on ZMZ-511, -513, -523 engines, the degree of purification of which is close to 99.5%. The filter element is located in a massive metal case with a lid fastened with five fasteners. With weak fasteners on the filter housing, the filter element is not pressed and passes air past itself. Loose fasteners are usually the result of backfiring into the carburetor when running on a cold engine or with incorrect adjustments. If you notice that some of the five fasteners are loose and rattling, try bending them, although this will require some effort. Fuzzy compression of the filter element inside the housing also occurs if its sealing rings on the end surfaces are made of hard rubber or plastic. When buying, pay attention to this, and do not take an element with a dubious sealing belt.

Rice. 18. View of the body of the float chamber:
1 - small diffusers; 2 - block of economizer and accelerator sprayers;
3 - large diffusers; 4 - idle fuel jets;
5 - plugs of idle air jets; 6 - main air jets;
7 - main fuel jets; 8 — economizer valve;
9 - accelerator pump discharge chamber

The second point is the condition of the engine. The fact is that it uses a closed crankcase ventilation system (Fig. 19). Crankcase gases, which are a mixture of exhaust gases that have penetrated into the crankcase through piston ring gaps, and oil vapors, are led by a special hose 3 into the space of the air filter for re-burning.

Rice. 19. Diagram of a closed crankcase ventilation system:
1 - air filter; 2 - carburetor; 3 — a hose of the main branch of ventilation;
4 — a hose of an additional branch of ventilation; 5 - oil separator;
6 - gasket; 7 - flame arrester; 8 - inlet pipe; 9 - fitting

The oil entrained by these gases must be separated in the oil separator 5 and if everything is in order, only traces of it are visible on the inner surface of the filter housing (with a paper filter element). However, when using a very bad oil, it actively oxidizes inside the engine, forming a huge amount of soot. When passing through the internal cavities of the engine, crankcase gases take with them particles of soot from the walls and carry them into the cavity of the air filter and further to the carburetor. Particles settle on the top cover of the carburetor and penetrate to the air jets, clogging them. Reducing the cross section of the air jets during clogging shifts the composition of the prepared mixture towards enrichment. This means, first of all, excessive fuel consumption and increased emission of toxic components.

Considering a closed ventilation system as unnecessary and harmful, drivers often remove the ventilation hose from the air filter. At the same time, such an amount of dirty air passes through the open ventilation fitting that it is no longer necessary to talk about the quality of filtration, and it is also surprising to quickly clog the carburetor (and engine wear).

The result of the operation of the crankcase ventilation system is a dark coating on all surfaces of the carburetor air path: on the walls of the neck, diffusers, dampers. It is not necessary to strive to completely clean it. Plaque adheres strongly to the walls, cannot fall into narrow calibrated channels and clog the jets.

From above, on the plane of the carburetor connector, idle fuel jets 4 are screwed (Fig. 18). The diameters of the channels of these jets are about 0.6 mm and the probability of clogging is high for them. Next to them, on the side of the body, under the plugs, idle air jets are screwed. Turn them out and make sure that both the jets and the air supply channels are clean.

It is better to clean the jets by wetting them with gasoline and at the same time cleaning them with a match or copper wire. Do this several times, gradually soaking hardened deposits. Do not use brute force - you can break the calibrated surface. As a result, the characteristic metallic sheen of the brass surface should appear on the jets.

At the bottom of the float chamber there is an economizer valve 8 (Fig. 18). To unscrew it, you must use a screwdriver with a wide sting. The valve is non-separable and is a threaded body, the valve itself and a spring that keeps it closed. The economizer valve in the free state must be tight. When tested on a specialized watering device under a water pressure of 1000 ± 2 mm, compressing the valve spring, no more than four drops per minute are allowed to fall. Otherwise, the valve is considered leaky and should be replaced.

Dismantling the float mechanism.

Remove the float shaft from the posts in the cover, now remove the float and float valve. The float in K-126 is brass, soldered from two halves, or plastic rarely fails, since the only thing that can happen to it is loss of tightness due to the fact that the float touches the walls of the float chamber. Examine the float; whether there are characteristic rubbing on it, especially on the lower part.

The valve assembly on the K-126 is quite reliable due to the polyurethane sealing washer installed on the valve shank. Inspect the valve and, above all, the sealing washer. It should not be rigid (which means the material is losing its properties, has grown old), should not become sour and be “sticky”. If the washer is normal, then other possible valve imperfections (skew, wear of the guide surface) will be compensated for by it. Look at the bottom of the valve body screwed into the carburetor body, where the sealing washer rests during operation. No dark marks should be visible on the surface, which are exfoliated particles of the washer material, a sure sign that the material is not real (real SKU-6 polyurethane is light). Clean them carefully, try not to leave scratches, which in the future will cause leaks.

If there is a suspicion that the washer is old or worn out, replace it. Remember that the quality of the valve mechanism is completely determined by the condition of the sealing washer, and the entire operation of the carburetor largely depends on the operation of the valve mechanism.

Air damper revision

On the cover there is an air damper with two valves, which forms the basis of the starting device. Turning the drive lever, make sure that the air damper in the closed position completely blocks the carburetor neck. If gaps remain along the perimeter of the damper, then you can slightly loosen the fastening screws without unscrewing them completely, and with the drive lever pressed, try to move the damper, achieving the tightest fit to the neck. Allowed gaps between the body and the damper are not more than 0.2 mm. After adjustment, securely tighten the fastening screws. It is not recommended to remove the air damper unless absolutely necessary. Remember that the fastening screws at the ends are riveted.
The air valves on the damper should move easily on their axes and fit tightly into place under the action of the springs.

Revision of the throttle actuator mechanism

Turn the carburetor over and remove the four screws securing the mixing chamber housing. In the free state, throttle valves 1 (Fig. 21) must be in the open position, since they are opened by a spring in the limiter housing. Rotate the throttle control lever and check that the throttles close smoothly without sticking. When the dampers are moved, a characteristic hiss of air in the supra-membrane cavity of the restrictor should be heard. This indicates the integrity of the membrane. If dampers do not open, check the condition of spring 1 (Fig. 20). To do this, open the cover of the restrictor diaphragm actuator. The spring may be broken or come off its pin. The tongue 3 on the two-arm lever adjusts the angle of inclination of the throttles when fully opened. It should be 8° to the vertical axis.

Rice. 20. View of the actuator
limiter (cover removed):
1 - spring, 2 - two-arm lever, 3 - tongue

Above the edges of the closed throttle valves, both openings of the adapter systems, one opening for vacuum extraction to the vacuum ignition timing regulator (at a height of about 0.2 ... 0.5 mm from the edge in one chamber) and the opening extraction of vacuum to the recirculation valve (at a height of about 1 mm from the edge in the other chamber).

Rice. 21. Housing of mixing chambers with limiter:
1 - throttle valves; 2 - air supply hole
to the membrane mechanism of the limiter; 3 - membrane mechanism;
4 - limiter housing; 5 - fuel supply holes
to "quality" screws and vias; 6 - screws "quality";
7 - vacuum extraction hole to the vacuum regulator
ignition timing

The incorrect position of the vias relative to the throttle valves disrupts the transition from the operation of the idle system to the operation of the main metering system. In addition, it indicates violations of the regulations. If the throttles are open at idle at a large angle (the vias are "hidden" under the edge), then a lot of air is supplied to the engine at idle through the throttle. The reasons are very different, for example, the mixture is too lean, the cylinder (or several) does not work, the channel of the small ventilation branch 9 is clogged (Fig. 19), through which a certain amount of air (together with crankcase gases) bypasses the carburetor.

Now unscrew the “quantity” screw almost completely. The dampers will close so that they will touch the walls of the mixing chamber. In this position, it is necessary that the gaps between them and the walls are almost absent and, if possible, equal. The tightness of closing the chokes is checked for clearance (it is necessary to look through the closed chokes at the light of the lamp). If the difference is large, you can slightly loosen the fastening screws without unscrewing them completely, and with the drive lever pressed, try to move the dampers, achieving the tightest fit to the walls. Allowed gaps between the housings and dampers are not more than 0.06 mm. Tighten the fastening screws and screw in the “quantity” screw until / so that the dampers are in the position described above relative to the vias. Remember this position of the screw, for example, by the location of the slot. This will help to adjust the engine when the carburetor is already in place.

In the usual case, a black layer of soot accumulates along the line of contact between the throttle and the wall, filling the gap between them. This "sealing" layer is not dangerous as long as it does not cover the vias. If in doubt, scrape off the carbon by soaking it in gasoline and clean all passages related to the transition systems.

Checking the condition of the accelerator pump

It comes down to the revision of the rubber cuff on the piston and the installation of the piston in the housing. The cuff must, firstly, seal the injection cavity and, secondly, move easily along the walls. To do this, its working edge should not have large scratches (folds) and it should not swell in gasoline. Otherwise, the friction against the walls may become so great that the piston may not move at all. When you press the pedal, the driver through the rod acts on the bar that carries the piston. The bar moves down, compressing the spring, and the piston stays in place.

Installing the piston and checking the performance of the accelerator pump is carried out after reassembling the carburetor. Before doing this, check the condition of the accelerator inlet valve, which is located at the bottom of the discharge chamber. It is a steel ball laid in a niche and pressed with a spring wire clip. Under this bracket, the ball can move about a millimeter freely, but cannot fall out of its niche. If the ball does not move, the bracket must be removed, the ball removed and its niche and channels thoroughly cleaned. The gasoline supply channel (under the ball) is drilled from the side of the float chamber. The channel draining gasoline to the atomizer is drilled from the opposite side of the body and plugged with a brass plug.

Rice. 22. View of the carburetor without a cover:
1 - economizer rod; 2 — strap drive economizer and accelerator;
3 - accelerator piston; 4 - main air jets;
5 - fuel supply screw of the accelerator pump;
6 - screws "quality *; 7 - screw "quantity"

Next, unscrew the brass fuel supply screw 5 (Fig. 22) and remove the sprayer unit of the accelerator pump and economizer. Immediately after this, turn the carburetor body over so that the accelerator discharge valve falls out (do not forget to put it in place when assembling). There are four nebulizers (two economizers and two accelerators) on the nebulizer block that need to be checked for cleanliness. Their diameter is about 0.6 mm, so use thin steel wire.

Take a thin rubber hose and blow through the channels from the accelerator pump chamber 9 (Fig. 18) and from the economizer 8 to the atomizer (the economizer must be turned out). If the channels are clean, then screw in the economizer, lower the accelerator pressure valve into place and screw on the atomizer block.
The pre-assembly of the carburetor begins with the mounting of the mixing chamber housing on the body of the float chamber. Preliminarily lay the gasket on the inverted housing, observing the position of the holes. On carburetors that were barbarously screwed to the engine, as a rule, the “ears” of the mount on the body were deformed. If you put a new gasket on them, then it will not shrink in the middle.

The deformed plane of the housing connector must be corrected

Check whether there are large diffusers 3 in the housing (Fig. 18), which could fall out during disassembly, and whether they are really of the diameter that is regulated * for this modification (overwhelmingly 27 mm). The size is applied on the upper end by casting. Now place the mixing chamber housing on top and fasten it with four screws.
Installation and testing of the accelerator pump and economizer. Insert the spring and the bar with the accelerator piston and the economizer rod into the body of the float chamber. Check the economizer activation points and accelerator piston stroke (Fig. 23). To do this, press bar 1 with your finger so that the distance between it and the connector plane is 15 ± 0.2 mm. At the same time, it is necessary to set a gap of 3 ± 0.2 mm between the end face of the nut and bar 1 with the adjusting nut 2 of the rod. After adjustment, the nut should be compressed.

This approach, given in all operating instructions, will ensure the correct moment for switching on the economizer only if the rod b (Fig. 17) of the accelerator pump drive lever has a standard length (98 mm). The indicated value of 15 ± 0.2 mm corresponds to the position of the bar with a fully open throttle. If the draft is shorter, the economizer will turn on earlier, and the piston stroke of the accelerator pump will become smaller. However, it is not worth trying to set the moment of switching on the economizer with particular accuracy. The moment of transition to enriched mixtures should occur when the throttle is opened by about 80%. At speeds up to 2500 min "', it would be possible to start enrichment even earlier, when the throttle was opened to half. Profitability does not suffer from this, but power, of course, does not increase. The position of the accelerator pump piston is not specified by the instructions. It is understood that it must rest against the bottom of the discharge chamber at the same time as the throttle is fully opened. Often the accelerator adjusting nut is tightened in the hope of increasing the feed (getting rid of "dips"). This does not change anything, since the piston stroke does not increase. It is better to monitor the state of the elements.

Rice. 23. Checking the moment when the economizer is switched on:
1 - drive bar; 2 — a nut of a rod of inclusion

Fill the float chamber with gasoline to the middle of the level. Since the accelerator pump drive does not work without a top cover, press the bar directly with your finger. Press sharply, and hold the bar for some time. At the same time, clear streams of gasoline should escape from the sprayers of the accelerator pump. Without the top cover, their direction, power and duration are clearly visible. Watch how the piston moves after pressing the bar. There should be no delay from the moment you press it to the moment the piston moves away. The total jet flow time (piston movement) is about a second. If there is a delay, if the jets are sluggish and flow for a long time, the piston cuff will have to be changed. If all of the above requirements are met, then we can assume that the accelerator pump as a whole is working.

If the piston moves and there is no flow through the atomizer, try running the accelerator without the atomizer. Unscrew the atomizer, remove the discharge valve and press the accelerator bar. Be careful not to lean too low - the jet of gasoline can hit high and hit your face. If no fuel comes out of the vertical channel, then the system of inlet channels from the piston is clogged. If fuel is flowing here, then clean the atomizer itself. If the atomizer is also clean and there is no flow through it, check if the discharge chamber under the piston is filling. Take out the piston and look into the camera. It must be full of gasoline. If it is not there, check the channels for supplying gasoline from the float chamber to the ball under the piston and the mobility of the ball itself. When the piston is pressed from the inlet channel, there should not be a breakthrough of the gasoline jet in the opposite direction (the ball valve is leaky). Be sure to check for the presence of the discharge valve (brass needle) under the atomizer block, it is easy to lose it.

In the future, you can quantify the feed. To do this, the carburetor assembly will need to be placed above the tank and ten times in a row, with a shutter speed of several seconds after pressing and after releasing, turn the throttle drive lever to the full stroke value. For ten full strokes, the accelerator pump must supply at least 12 cm3 of gasoline.

Setting the fuel level

Take the carburetor cover, insert a needle with a serviceable sealing washer into the valve body of the float mechanism, put the float and insert its axis (Fig. 8). Holding the cap upside down as shown in the figure, measure the distance from the edge of the float to the plane of the cap. Distance A must be 40 mm. The adjustment is made by bending the tongue 4, which rests against the end of the needle 5. At the same time, make sure that the tongue always remains perpendicular to the valve axis, and there are no notches or dents on it! At the same time, by bending the limiter 2, it is necessary to set the gap B between the end of the needle 5 and the tongue 4 within 1.2 ... 1.5 mm. On carburetors with a plastic float, gap B is not adjustable.

By setting the position of the float in this way, we, unfortunately, cannot guarantee the complete tightness of the valve assembly. Try to put the cover vertically, with the float hanging down, and put a thin rubber hose with marked ends on the fuel supply fitting. It is very convenient to have such a hose, you just need to mark the ends so that one always remains clean. Pressurize the valve with your mouth and slowly turn the cap so that the float changes its position relative to it. The position at which air leakage stops should correspond to a distance between the float and the body, approximately equal to dimension A.

Now create a vacuum in the hose and evaluate the leak. If the valve is tight, then the vacuum remains unchanged for a long time. In the presence of non-densities of any kind, the vacuum created by you quickly disappears. If there is no tightness, then the sealing washer must be replaced. In some cases, the fit of the valve body itself on the threads may be leaky. Try to trust him. Remember that the entire operation of the carburetor largely depends on the operation of the valve mechanism.

Carburetor assembly

First of all, put in place all the jets that you unscrewed in the carburetor body. Screw them in securely, but without undue force, so as not to damage the slot and make it easier to unscrew later. Install the spring and bar with the accelerator piston and economizer rod. Lay the gasket on the housing connector plane. The carburetor cover, pre-assembled, is installed from above and should easily lie in place and center. Finally tighten the seven cover screws.

Try how the accelerator pump drive lever turns after assembly. It should move easily and at the same time move the accelerator pump. If the lever does not move, it means that it was stuck in the wrong position during assembly. Remove the cover and start over.
Align the notch on the throttle lever with the mustache on the accelerator link. In a certain position, they will coincide, and the rod will be inserted into the lever. Insert the upper end of the rod into the hole and pin. Do not forget which of the two possible holes in the lever was the rod before disassembly! By turning the throttle drive lever, check now whether the piston of the accelerator pump is moving smoothly.

For convenience, you can even remove the top small cover that covers the drive lever with the roller pressing the bar. In the position of the throttle drive lever on the idle stop, there should be no gap between the roller and the bar. The slightest movement of the lever should move the bar and accelerator piston. Let me remind you that the K-126 is extremely demanding on the operation of the accelerator pump, the ease of operation of the car largely depends on the quality of its work.

Trigger Adjustment

carried out on a fully assembled carburetor. Turn the choke lever all the way. The throttle should now be ajar at a certain angle, which is estimated from the gap between the edge of the throttle valve and the chamber wall (see Fig. 14). In the "starting" position, it should be approximately 1.2 mm. The gap is adjusted as follows. Having loosened the fastening of the adjusting bar 3, located on the lever 4 of the accelerator pump drive, completely close the carburetor air damper with the lever 5.

Next, the throttle valves are slightly opened with lever 1 so that the gap between the wall of the mixing chamber and the edge of the damper is 1.2 mm. You can insert a wire with a diameter of 1.2 mm into the gap between the edge of the throttle and the body of the mixing chamber and release the throttle so that it is pinched in the gap. Next, the adjusting bar 3 is moved until it rests against the ledge of the lever, after which it is fixed. Several times, by opening and closing the air damper, check that the specified gap is set correctly. Given that the starting device on the K-126 has practically no automation, ajar throttle is fundamentally important when starting a cold engine.

Mounting the carburetor

After all carburetor systems have been inspected, the cavities have been flushed, the adjusting clearances have been set, the carburetor must be correctly installed on the engine. If you did not remove the gasket from the engine intake pipe when dismantling, then feel free to install the carburetor in place. Otherwise, make sure that the gasket is laid in the same way as before. Incorrect orientation is dangerous because the prints of the channels of the lower part of the carburetor on the gasket will move to new places, and air will be sucked into the recesses formed.

Do not try to tighten the carburetor fastening nuts very much - you will deform the platforms. Insert the strut with a spherical head, which we left on the rod from the pedal, into the throttle drive lever, and tighten the nut from the inside. Install the return spring, the gasoline supply hose, the vacuum take-off to the vacuum ignition timing regulator and the recirculation valve. Fasten the rod shell and the air damper rod itself.

Checking control mechanisms.

Pull out the choke control knob on the panel in the cabin to the stop and evaluate how clearly the choke on the carburetor closed. Now drown the handle and make sure that the air damper has opened completely (it has risen strictly vertically). If this does not happen, loosen the sheath fixing screw and pull the sheath a little further. Tighten the screw and check again. Remember that an incorrect position of the air damper with a recessed drive button leads to increased fuel consumption.

When the throttle valves are fully opened, the “gas” pedal in the cabin must necessarily rest against the floor mat. This prevents the occurrence of excessive stresses in the drive parts and increases their durability. Ask your partner to press the pedal in the cabin to the floor, and evaluate the degree of throttle opening on the carburetor yourself. If the throttle can be turned further by hand to any angle, shorten the length of the drive rod by screwing the tip deeper.

After the final adjustment, the pedal at full throttle should be pressed to the floor, and when the pedal is released, there should be some free play in the rods.

Fuel level control

should be carried out after the final installation of the carburetor on the engine. Older carburetors had a viewing window through which the level was visible. In the latest modifications, there is no window, and there is only risk 3 (Fig. 9) on the outer side of the case. For control, it is necessary to screw in instead of one of the plugs 2 that block access to the main fuel jets, a fitting with the appropriate thread, and put a piece of a transparent tube on it (Fig. 24). The free end of the tube should be raised above the parting line of the housings. Using the manual lever, fill the fuel pump, the float chamber with gasoline.

According to the law of communicating vessels, the level of gasoline in the tube and in the float chamber itself will be the same. By attaching the tube to the wall of the float chamber, it is possible to assess the coincidence of the level with the risk on the body. After measuring, drain the fuel from the float chamber through the tube into a small container, excluding it from getting on the engine, unscrew the fitting and screw the plug back into place. Simultaneously with checking the level, the absence of leaks through gaskets, plugs and plugs is checked.

Fuel level label

Rice. 24. Scheme for checking the fuel level in the float chamber:
1 - fitting; 2 - rubber tube; 3 - glass tube

If the fuel level does not match the mark by more than 2 mm, you will have to remove the cover and repeat the leveling of the float chamber by bending the tongue.

Idle presetting. Starting the engine after installing the carburetor may take longer than usual, because the float chamber is empty and the fuel pump will take time to fill it. Close the choke completely and start the engine with the starter. If the fuel supply system (primarily the fuel pump) is working, then the start will occur in 2 ... 3 seconds. If after even twice as long there are no outbreaks, then there is reason to think about the presence of gasoline or the serviceability of the fuel supply system.

Warm up the engine by gradually pushing the choke knob in and not letting it develop too high a speed. If you managed to completely remove the drive handle and the engine is idling on its own (even if not very stable), proceed to the final idle adjustment.

If the engine refuses to work when the gas pedal is released (or is very unstable), start a rough adjustment of the idle system. To do this, hold the throttle with your hand so that the engine runs as slowly as you can hold it (the rotational speed is about 900 min "1). Do not touch the "quantity" screw. When inspecting the throttle valves, it had to be set to the “correct” position in relation to the vias. In extreme cases, you can temporarily move the screw, remembering how much you turned it.

Try adding fuel by loosening the "quality" screws. If the engine is running more stable, then you are on the right track. If the speed began to fall, you should move in the direction of depletion (reducing the feed). If, despite all the manipulations with the “quality” screws, the engine does not start to work more stable, the reason may be that the float chamber valve is not tight. The fuel level rises uncontrollably, becomes higher than the edge of the atomizer, and gasoline begins to spontaneously flow into the diffusers. The mixture is enriched and may even go beyond the ignition limits.

The opposite situation is that the channels in the idle system are clogged and fuel does not flow at all. The smallest section is in the idle fuel jet. This is where the risk of contamination is highest. While holding the throttle with your hand, try to unscrew one of the idle fuel jets 9 by half a turn with the other hand (Fig. 22). When the idle jet moves away from the wall, a huge (by its standards) gap is formed, into which gasoline is sucked out along with debris by the high vacuum in the channels. The mixture at the same time becomes over-enriched, and the engine will begin to "lose" speed.

Do this operation several times, then wrap the jet, finally. Repeat the operation with another jet. If, on a slightly turned jet, the engine can independently idle, and when screwing it back into place, the engine stalls, either the jet itself (firmly) or the idle channel system is clogged.
Alternatively, it is possible that it is not the carburetor that is to blame for the unstable operation, but the SROG exhaust gas recirculation system valve. It is installed on engines relatively recently (Fig. 25).

Srog serves to reduce emissions of nitrogen oxides with exhaust gases by supplying part of the exhaust gases from manifold 1 to the intake tract through a special spacer 4 under the carburetor 5. The operation of the recirculation valve is controlled by vacuum from the throttle body, taken through a special fitting 9 (Fig. 17) .

At idle, the SROG system does not work, since the vacuum extraction hole is located above the throttle edge. But if the recirculation valve does not completely block the channel, then the exhaust gases can enter the intake pipe and lead to a significant dilution of the fresh mixture.

Idle system adjustment

After the elimination of defects, it is possible to carry out the final adjustment of the idle system. Adjustment is made using a gas analyzer according to the method of GOST 17.2.2.03-87 (as amended in 2000). The content of CO and CH is determined at two crankshaft speeds: minimum (Nmin) and increased (Np.), equal to 0.8 Nnom. For ZMZ eight-cylinder engines, the minimum crankshaft rotation Nmin= 600±25 min-1 and Nrev= 2000+100 min"1.

Rice. 25. Exhaust gas recirculation scheme:
I - recirculated gases; II - control vacuum;
1 - intake manifold; 2 - recirculator tube;
3 - hose from the thermal vacuum switch to the carburetor;
4 - spacer recirculation; 5 carburetor;
6 - hose from the thermal vacuum switch to the recirculation valve;
7 - thermal vacuum switch; 8 recirculation valve;
9 - recirculation valve stem

For cars produced after 01/01/1999, in the technical documentation for the car, the manufacturer must indicate the maximum allowable carbon monoxide content at the minimum speed. Otherwise, the content of harmful substances in the exhaust gases must not exceed the values given in the table:

For measurements, it is necessary to use a continuous infrared gas analyzer, having previously prepared it for operation. The engine must be warmed up to at least the operating temperature of the coolant specified in the vehicle manual.

Measurements should be carried out in the following sequence:

set the gear lever to the neutral position;
brake the car with a parking brake;
turn off the engine (when it is running), open the hood and connect the tachometer;
install the sampling probe of the gas analyzer into the vehicle exhaust pipe to a depth of at least 300 mm from the cut;
fully open the carburetor choke;
start the engine, increase the speed to Npov and work in this mode for at least 15 seconds;
set the minimum speed of the engine shaft and, not earlier than after 20 s, measure the content of carbon monoxide and hydrocarbons;
set an increased engine shaft speed and, not earlier than after 30 s, measure the content of carbon monoxide and hydrocarbons.
In case of deviations of the measured values from the standards, adjust the idle system. At the minimum speed, it is enough to influence the screws of "quantity" and "quality". Regulation is carried out by successive approximation to the “target”, correcting one and the other screw in turn until the required values of CO and CH are reached at a given frequency Nmin. You should always start with “quality”, so as not to knock down the setting of the position of the throttles relative to the vias. If, after adjusting the composition of the mixture with the “quality” screws alone, the engine speed goes beyond 575 ... 625 min "1, use the "quantity" screw.

Since there are two independent idle systems on the K-126, the adjustment of the composition of the mixture has its own characteristics. When changing the composition of the mixture with the “quality” screw, the rotational speed can simultaneously change. Rotating one of the “quality” screws, find its position at which the rotational speed will be maximum. Leave it and do the same with the second screw. In this case, the readings of the gas analyzer for CO will probably be about 4%. Now we turn both screws synchronously (at the same angles) until the required CO content is obtained.

The hydrocarbon content is determined more by the general condition of the engine than by carburetor adjustments. A serviceable engine is easily tuned to CO values of about 1.5% at CH values of approximately 300 ... 550 million "'. There is no point in chasing smaller values, since the stability of the engine is significantly reduced while increasing consumption (contrary to popular belief). If hydrocarbon emissions exceed the given average values by several times, the cause must be sought in an increased breakthrough of oil into the combustion chamber. These can be worn valve stem seals, broken valve bushings, incorrect adjustment of thermal clearances in the valves.

GOST limit values of 3,000 ppm1 are achieved on worn out, misaligned, oil-consuming engines, or when one or more cylinders are not working. A sign of the latter can be very small values of CO emissions.

In the absence of a gas analyzer, almost the same control accuracy can be achieved using only a tachometer or even by ear. To do this, on a warm engine and with the “quantity” screw position unchanged, find, as described above, such a position of the “quality” screws, which provides the maximum engine speed. Now, with the “quantity” screw, set the rotational speed to approximately 650 min. ”1. Check with the "quality" screws whether this frequency is the maximum for the new position of the "quantity" screw. If not, repeat the whole cycle again to achieve the required ratio: the quality of the mixture provides the highest possible speed, and the number of revolutions is approximately 650 min. Remember that the "quality" screws must be rotated in sync.

After that, without touching the "quantity" screw, tighten the "quality" screws so much that the rotational speed decreases by 50 min "1, i.e. to the regulated value. In most cases, this adjustment meets all the requirements of GOST. Adjustment in this way is convenient because it does not require special equipment, and can be carried out every time the need arises, including for diagnosing current state power systems.

In the event that CO and CH emissions do not comply with GOST standards at an increased speed (Npov "= 2000 * 100 min" '), the impact on the main adjusting screws will no longer help. It is necessary to check if the air jets of the main metering system are dirty, if the main fuel jets are enlarged and if the fuel level in the float chamber is excessive.

Checking the pneumocentrifugal speed limiter is quite complicated and requires the use of special equipment. Checking is subject to the tightness of the valve in the centrifugal sensor, the correct adjustment of the sensor spring, the tightness of the membrane, the jets of the actuator. However, you can check the performance of the limiter directly on the car. To do this, on a well-heated and adjusted engine, the throttle valves are fully opened and the crankshaft speed is measured with a tachometer.
The limiter works correctly if the speed is within 3300 + 35 ° min "1.

If you decide to carry out such a check, get ready in case of unforeseen engine accelerations to have time to “reset” the throttle. If everything is in order, then acceleration to such a frequency does not pose any danger to the engine. Many drivers turn off the limiter themselves to get extra power at higher revs. Sometimes, the actuation of the limiter, for example when overtaking, can indeed cause an unwanted delay associated with the need to shift gears.

But even shutdown should be carried out correctly. The widespread disconnection of the tubes from the centrifugal sensor leads to a constant overflow of dirty air from the street under the throttle valves. If the tubes are plugged after disconnection, then the membrane actuator will work (close the throttle).

If the limiter is correctly turned off, the chamber should be closed, bypassing the centrifugal sensor. To do this, one of the tubes from the membrane chamber (for example, from outlet 1 in Fig. 9) should be screwed into the second outlet 7 of the same chamber

Possible malfunctions of the fuel supply system and methods for their elimination

Sometimes, and subject to the maintenance intervals, situations may arise when the carburetor fails. When troubleshooting, first of all, it is necessary to determine the system or node that can give the existing defect. Very often, the carburetor is attributed to engine malfunctions, the true cause of which is, for example, the ignition system. She generally acts as a "culprit" more often than is commonly believed.
To exclude the influence of one system on another, it is necessary to clearly understand that the carburetor power system is inertial, i.e. changes in its work can be traced in several successive engine cycles (their number can be measured in hundreds). It is not able to make any changes to the work of one working cycle (this is at most 0.1 seconds). The ignition system, on the contrary, is responsible for each individual cycle in the operation of the engine. If there are skips of individual cycles, manifested in the form of short jerks, then with a high probability the reason is precisely in it.

Of course, the division of powers of the systems is not so unambiguous. The fuel supply system is not able to "shut off" one cycle, but can create conditions for unfavorable operation of the ignition system, for example, by excessively lean mixture. In addition, there are a number of subsystems in the fuel supply system, each of which can make its own characteristic "contribution" to the operation of the engine.

In any case, before you start looking for defects in the carburetor, or even adjusting it, you need to make sure that the ignition system is working. The main argument in defense of the ignition system - “there is a spark” - cannot serve as proof of serviceability.

It is very difficult to verify the energy parameters of the ignition system. A spark can be supplied at the right moment, but carry with it several times less energy than is necessary for reliable ignition of the mixture. This energy is sufficient for engine operation in a narrow range of mixture compositions, and is clearly not enough for guaranteed ignition in cases of the slightest deviation (depletion associated with acceleration, or enrichment during cold start-warm-up).

For the ignition system, only the setting advance angle (the position of the spark relative to TDC) is regulated at the minimum idling speed. Its value for engines ZMZ 511, -513 ... is 4 ° of crankshaft rotation after (!) TDC. At other frequencies and loads, the ignition timing is determined by the operation of the centrifugal and vacuum regulators located in the distributor. Their impact on performance (primarily fuel consumption and power) is enormous. How the regulators work, how accurately they set the lead angles in each of the modes can only be checked on special stands. Sometimes the only way to troubleshoot is to sequentially replace all elements of the ignition system.

Before examining the carburetor, you must also make sure that the rest of the fuel supply system is working. This is the fuel supply line from the gas tank to the fuel pump (including the fuel intake in the tank), the fuel pump itself and fine fuel filters. Clogging of any of the elements of the tract leads to a restriction in the supply of fuel to the engine.

Feed restriction is understood as the impossibility of creating a fuel consumption greater than a certain value. Engine power is inextricably linked with fuel consumption, which will also have a certain limit. Therefore, in the event of a fuel failure, your car will not be able to move at maximum speeds or uphill, but this will not prevent it from idling properly or when driving uniformly at low speeds.

Another sign of limited fuel supply is not the instantaneous manifestation of a defect. If you have idling for at least a minute and immediately drove with a heavy load, then the supply of gasoline in the carburetor float chamber will provide the possibility of normal movement for some time. Fuel "starvation" caused by the supply restriction, the engine will begin to feel as the reserve is exhausted (at a speed of 60 km / h, you can drive about 200 meters on the amount of gasoline that is in the float chamber).

To check the fuel supply, disconnect the supply hose from the carburetor, and direct it into an empty bottle of 1.5 ... 2 liters. Start the engine on the remaining gasoline in the float chamber and watch how the gasoline flows. If the system is in good order, the fuel comes out in a powerful pulsating jet with a cross section equal to that of the hose. If the jet is weak, try to repeat everything by disconnecting the fine fuel filter. Naturally, if there is an effect, the filter that needs to be replaced is to blame.

You can check the section of the highway to the fuel pump only by blowing it in the “reverse direction. You can even do this with your mouth, remembering to open the cork on the gas tank. The line should be blown relatively easily, and in the tank itself a characteristic gurgling of air passing through gasoline should be heard.
After checking the lines before and after the fuel pump and not achieving an effect, check the fuel pump itself. A small mesh is installed in front of its intake valves. If contamination is excluded, check the tightness of the pump valves or the operability of its drive from the engine camshaft.

After making sure that the ignition system is working and the supply part of the power system is working, you can begin to identify possible defects in the carburetor. This section is independent and you can carry out troubleshooting work without prior maintenance and adjustment of the carburetor. Most often, such work has to be performed in case of malfunctions that do not generally affect operation, but cause certain inconveniences. These can be all sorts of "failures" when opening the throttle, unstable idling, increased fuel consumption, sluggish acceleration of the car. Situations are much less common when, for example, the engine does not start at all. In such cases, as a rule, it is much easier to find and fix the problem. Remember one thing: all carburetor malfunctions can be reduced to two - either it is preparing too rich or too lean mixture!

Engine won't start

There can be two reasons for this: either the mixture is too rich and goes beyond the ignition limits, or there is no fuel supply and the mixture is too lean. Re-enrichment can be achieved both due to incorrect adjustments (which is typical for a cold start), and due to a violation of the tightness of the carburetor when the engine is stopped. Re-leaning is a consequence of incorrect adjustments (during a cold start) or lack of fuel supply (clogging).

If no flashes occurred during the starter cranking, there is most likely no fuel supply at all. This is true for cold and hot starts. On a hot engine, for greater reliability, close the choke a little and repeat the start again. The same reason may also be to blame if, when the starter was cranking, the engine made several flashes or even worked for a few moments, but then fell silent. Just gasoline was only enough for a short time, for several cycles.

Make sure the fuel supply line is working. Remove the air filter cover and, opening the throttle valves with your hand, see if there is a stream of gasoline coming from the accelerator pump nozzles. The next step will probably be to remove the top cover of the carburetor and see if there is gasoline in the float chamber (unless, of course, there is a viewing window on the carburetor).

If there is gasoline in the float chamber, then the cause of the difficult start of a cold engine may be a loose closing of the air damper. This may be due to misalignment of the damper on the axis, tight rotation of the axis in the housing or all links of the trigger, improper adjustment of the trigger. Too lean a mixture during a cold start is unable to ignite, but at the same time carries enough gasoline with it to “fill in” the spark plugs and stop the start-up process already due to the lack of a spark.

A hot engine, in the presence of gasoline in the float chamber, must be started, at least with the air damper covered, except in the case of complete clogging of the main fuel jet. On a hot engine, the reverse situation is more likely, when the engine does not start from over-enrichment. The fuel pressure after the fuel pump is stored for a long time in front of the float chamber valve, loading it. A worn valve cannot handle the load and leaks fuel. Having evaporated from heated parts, gasoline creates a very rich mixture that fills the entire intake tract. When starting, you have to crank the engine for a long time with a starter to pump all the gasoline vapors until a normal mixture is organized. It is advisable to keep the throttle valves open.

When starting a cold engine, we artificially create a rich mixture, and over-enrichment associated with valve leaks will not be noticeable against the general background of a rich mixture. During a cold start, the trigger mechanism is more likely to be incorrectly adjusted, for example, a small amount of throttle opening by the opener rod.

Unstable idle.

In the simplest case, the reason lies in the improper adjustment of idle systems. As a rule, the mixture is too lean. Enrich it with “quality” screws, if necessary, adjust the rotational speed with the “quantity” screw.
If there is no visible effect when adjusting, the cause may be a leak in the float chamber valve. Gasoline leakage leads to uncontrolled re-enrichment of the mixture. On carburetors with a viewing window, the fuel level is higher than the glass.

Try turning the idle fuel jets tighter. If they do not touch the body with a sealing belt, the gap formed acts as a parallel jet, significantly enriching the mixture. Perhaps the jets are installed with greater performance than expected.
It happens that unstable operation is caused by insufficient supply of gasoline due to a clogged idle system. The highest probability of clogging is in the idle fuel jet, where the smallest section is. Try to clean it in the way that is described in the "idle presetting" section.

Inability to adjust the engine at idle.

When adjusting the engine, a situation may arise when, with overall performance, it cannot be adjusted for toxicity. This is manifested in increased emissions of CO and CH, which cannot be eliminated by adjusting screws.
The reason for a very rich mixture and increased CO emissions, as a rule, is not the tightness of the float chamber (within insignificant limits, otherwise the engine simply refuses to work in this mode), clogging of idle air jets 8 (Fig. 22) with solid particles or resins, increased cross section main fuel jets 7 (Fig. 18) or idle fuel jets 4.

If the level of CH hydrocarbons is high, the cause should be sought in the over-leaning of the mixture associated with incorrect adjustments, contamination, or in the shutdown of one of the cylinders. It should be remembered that toxicity adjustments are largely determined by the condition of the engine as a whole. Check and adjust the thermal clearances in the valve mechanism of the engine. Do not try to make them smaller than what is prescribed in the engine manual. Assess the condition of high-voltage wires, ignition coils, spark plugs.

Remember that candles age irreversibly.

Failure at smooth opening of the throttle. If the engine runs steadily at idle, obeys the “quality” and “quantity” screws, but does not accelerate or behaves very unstable when the throttle is opened smoothly, the condition of the transitional systems should be checked. For a complete check, it is necessary to remove the carburetor and assess the condition of the vias. The latter may be clogged with soot or located too low relative to the throttle edge. In the latter case, traces of gasoline are visible on the walls of the mixing chambers, which flows from the vias at idle (which should not be). At the same time, their contribution to the increase in fuel consumption as the throttle is opened becomes small, which leads to over-depletion of the mixture during the transition (until the main metering system is turned on).

Try to set the throttle as low as possible so that the vias are not visible from below in the closed position. By closing the throttle, we limit the air supply (reduce speed) and therefore, at the same time, it is necessary to compensate for the air flow through the throttles either by flow through other sections or by greater work efficiency.
Check the cleanliness of the channel of the small ventilation branch 9 (Fig. 19), make sure that all cylinders work and that the ignition is not set too late.

With a smooth opening of the throttle, a malfunction of the transitional system will manifest itself until a certain moment, where the main dosing system will come into operation. If, however, with this opening, the operation of the engine does not improve even at a high speed of rotation, if the car twitches when driving at partial loads at a constant speed, if the behavior becomes much better when the throttles are fully opened (sometimes the engine does not work at all if the throttle is not fully opened), then you should check the condition of the main fuel jets. Unscrew plugs 2 (Fig. 9) in the carburetor body and unscrew fuel jets 7 (Fig. 18). See if there are any particles on them. As a rule, there is a small grain of sand that closes the passage section.

If the jet is clean, and the behavior of the car obeys the described patterns, it can be assumed that the entire fuel path of the main metering system (emulsion well, outlet channel to the atomizer, incorrect setting of small diffusers) is contaminated or the jet marking does not match the required one. The latter most often occurs when replacing regular factory jets with new ones from repair kits. Do not try to enrich the mixture with “quality” screws, this will not help in this situation, since they only affect the idle system adjustments.

Throttle dip, which disappears after the engine has been “running” for 2…S seconds, may indicate defects in the accelerator pump. The accelerator pump on the K-126 is an element of fundamental importance and the whole operation of the carburetor largely depends on how it works. Even with smooth throttle opening, a mode in which other carburetors do not need an accelerator, injection lag associated with backlash in the drive or piston friction can lead to engine stall. Check again all the items mentioned in the "checking the condition of the accelerator pump" section. If elements were replaced, remember the possible quality of the rubber cuff on the accelerator piston. There is no need to strive to increase the stroke of the accelerator, since this will only increase the duration of injection, and the need for additional fuel is manifested from the very first moments of opening the throttle. It is important that during this period a sufficient amount of gasoline is supplied.

Increased fuel consumption.

The cherished desire of any driver is to reduce the fuel consumption of the car. Most often, they try to achieve this by influencing the carburetor, forgetting that fuel consumption is a value determined by a whole complex of devices.

Fuel is spent on overcoming various resistances to the movement of the car, and the amount of consumption depends on how great these resistances are. You should not expect high results in fuel efficiency of a car whose brake pads do not completely diverge or the hub bearings are overtightened. A huge amount of energy is spent on scrolling the transmission and engine elements in winter, especially when using thick viscous oils. A major consumer of energy is speed. Here, in addition to friction losses of mechanisms, aerodynamic losses are added. And a very large item of energy expenditure is the dynamics of the car. To move at a constant speed of 60 km/h, the PAZ bus needs about 20 kW of engine power, while for acceleration from 40 km/h to 80 km/h we use an average of about 50 kW. Each stop “eats up” this energy, and for the next acceleration we are forced to spend more.

The working process of each engine, the degree of conversion of fuel energy into work, has its own limitations. For each modification, the compositions of the mixture and the ignition timing are determined, which give the required output parameters in each mode. The requirements for each mode may be different. For some, this is efficiency, for others - power, for others - toxicity.

The carburetor acts as a link in a single complex that implements known dependencies. One cannot hope to reduce fuel consumption by reducing the orifice of the jets. The reduction in the amount of fuel passing will not be consistent with the amount of air. Sometimes it is more expedient to increase the flow area of the fuel jets in order to eliminate the depletion inherent in all modern carburetors. This will be especially pronounced when operating the car in winter, at low ambient temperatures. All carburetor adjustments are selected for the case of a fully warmed up engine. Some enrichment can bring the mixture closer to the optimum in cases where your engine is below operating temperature (for example, in winter with relatively short trips). In any case, it is necessary to strive to increase the temperature of the coolant. It is unacceptable to operate the engine without a thermostat; in winter conditions, measures should be taken to insulate the engine compartment.

Carry out the entire complex of carburetor adjustments yourself. Pay attention to:
correspondence of jets to the brand of carburetor;
the correct adjustment of the starting device, the completeness of the opening of the air damper;
no leakage of the float chamber valve;
idle system adjustment. Do not try to make the mixture poorer, this will not reduce consumption, but will increase the problems of transition to load modes;
check the condition of the engine itself. Particles or grains of sand flying from the ventilation system with a leaky air filter can clog the air jets, improper adjustment of the clearances in the valve mechanism will lead to unstable idling, small values of the ignition timing will directly cause increased consumption;
make sure that there is no direct leakage of fuel from the fuel line, especially in the area after the fuel pump.
Given the complexity and diversity of operating factors, it is impossible to give uniform recommendations for reducing operating costs. Methods that are acceptable for one driver may be completely unsuitable for another simply because of differences in driving style or choice of driving modes. It is probably advisable to recommend that you fully trust the factory settings and the dimensions of the dosing elements. It is unlikely that by changing the cross section of any jets, it will be possible to significantly change the efficiency of the engine. Perhaps this will only work out to the detriment of some other parameters - power, dynamism. Remember that those who created the carburetor and selected jets for it stood in the strict framework of the need to comply with many diverse and conflicting conditions. Don't think you can get past them. Often, the useless search for new global solutions leads away from simple, elementary methods of car maintenance, which make it possible to achieve quite acceptable, but real efficiency. Wouldn't it be better to direct efforts in this direction, since miracles, unfortunately, do not happen.

The engine is equipped with a K-126G carburetor - emulsion, two-chamber, with a falling flow, with sequential opening of throttle valves and a balanced float chamber.

The carburetor has two mixing chambers: primary and secondary. The primary chamber operates in all engine modes. The secondary chamber is activated under heavy load (after approximately 2/3 of the primary chamber throttle stroke).

To ensure uninterrupted operation of the engine in all modes, the carburetor has the following metering devices: primary chamber idle system, secondary chamber transition system, primary and secondary chamber main metering systems, economizer system, cold engine start system and accelerator pump system. All elements of dosing systems are located in the body of the float chamber, its cover and the body of the mixing chambers. The body and cover of the float chamber are cast from zinc alloy TsAM-4-1. The body of the mixing chambers is cast from aluminum alloy AL-9. Sealing cardboard gaskets are installed between the body of the float chamber, its cover and the body of the mixing chambers.

Rice. 1. Carburetor K-126G (section 1):

1. Mixing chamber; 2. Mixture quality screw; 3. Vacuum regulator hole; 4. Throttle actuator lever; 5. Screw the amount of mixture; 6. The diffuser is large; 7. Diffuser small; 8. Air damper axis; 9. Choke spring; 10. Cover of the float chamber; 11. Air damper; 12. Accelerator pump atomizer; 13. Fuel jet idling; 14. Body of the float chamber; 15. Viewing window; 16. Throttle valve.

Rice. 2. Carburetor K-126G (section 2):

17. Housing fixing screw; 18. Cover screw; 19. Economizer atomizer; 20. Accelerator pump drive; 21. Main air jet; 22. Filter plug; 23. Emulsion tube; 24. Accelerator pump piston; 25. Drive link; 26. The axis of the secondary throttle.

Rice. 3. Carburetor K-126G (sections 3 and 4):

27. Guide sleeve; 28. Main fuel jet; 29. Float; 30. Fuel valve; 31. Fuel filter.

In the body of the float chamber are located:

two large 6 and two small diffusers 7 ;

Two main fuel jets 28 ;

Two air brake jets 21 main dosing systems;

Two emulsion tubes 23 located in wells;

fuel 13 and air jets of the idle system;

Economizer and guide sleeve 27 ;

accelerator pump 24 with pressure and check valves.

The atomizers of the main dosing systems are led into small diffusers of the primary and secondary chambers. The diffusers are pressed into the body of the float chamber. There is a window in the body of the float chamber 15 to monitor the fuel level and the operation of the float mechanism.

All channels of the jets are equipped with plugs to provide access to them without disassembling the carburetor. The idle fuel jet can be turned out from the outside, for which its body is brought out through the cover up.

The air damper is located in the cover of the float chamber. 11 with semi-automatic drive. The air damper drive is connected to the throttle valve axis of the primary chamber by a system of levers and rods, which, when starting a cold engine, open the throttle valve to an angle necessary to maintain the starting engine speed. The secondary throttle valve is tightly closed.

This system consists of an air damper drive lever, which with one shoulder acts on the air damper axle lever, and with the other through a rod on the idle throttle lever, which, turning, presses the primary chamber damper and opens it.

A float mechanism is attached to the carburetor cover, which consists of a float suspended on an axis and a valve 30 fuel supply. The carburetor float is made of 0.2 mm thick brass sheet. Fuel supply valve - collapsible, consists of a body and a shut-off needle. Valve seat diameter 2.2 mm. The cone of the needle has a special sealing washer made of a fluorine rubber compound.

Fuel entering the float chamber passes through a strainer 31 .

There are two throttle valves in the body of the mixing chambers 16 primary chamber and secondary chamber, adjusting screw 2 idle system, toxicity screw, channels of the idle system, through hole of the idle system, which serves to ensure coordinated operation of the idle system and the main dosing system of the primary chamber, hole 3 vacuum supply to the ignition timing vacuum regulator, as well as the transition system of the secondary chamber.

The main carburetor systems work on the principle of pneumatic (air) fuel braking. The economizer system works without braking, like an elementary carburetor. Idling, accelerator pump and cold engine start systems are available only in the primary chamber of the carburetor. The economizer system has a separate atomizer 19 , brought into the air pipe of the secondary chamber. The secondary chamber is equipped with an idle transition system.

Rice. 4. Carburetor K-126G (section 5).

The carburetor idle system consists of a fuel jet 13 , air jet and two holes in the primary mixing chamber (upper and lower). The bottom hole is provided with a screw 2 to control the composition of the combustible mixture. The idle fuel jet is located below the fuel level and is connected after the main jet of the primary chamber. Emulsification of fuel is carried out by an air jet. The required performance of the system is achieved by the idle fuel jet, air brake jet, as well as the size and location of the vias in the primary mixing chamber.

The main dosing system of each chamber consists of large and small diffusers, emulsion tubes, main fuel and main air jets. Main air jet 21 regulates the flow of air into the emulsion tube 23 located in the emulsion well. The emulsion tube has special holes designed to obtain the required performance of the system.

The idling system and the main metering system of the primary chamber provide the necessary fuel consumption in all main engine operating modes.

The economizer system consists of a guide bush 27 , valve and nozzle 19 . The economizer system is put into operation 5-7° before the throttle valve of the secondary chamber is fully opened.

It should be noted that, in addition to the economizer system, the main metering systems of both chambers operate at full load and very little fuel continues to flow through the idle system.

The accelerator pump system consists of a piston 24 , drive mechanism 20 intake and delivery (exhaust) valves and atomizer 12 , brought into the air pipe of the primary chamber. The system is driven by the throttle axis of the primary chamber and operates when the vehicle is accelerating.

A lever is rigidly fixed on the axis of the throttle valve of the primary chamber 4 drive. The backstage leash is also rigidly fixed on the axis 25 . The link is freely installed on the damper axis 16 and has two grooves. In the first of them, the leash moves, and in the second - a finger with a lever roller attached to it 26 axle drive 8 secondary damper.

The shutters are held in the closed position by springs attached to the axis of the primary chamber and the axis of the secondary chamber. backstage 25 also constantly tends to close the shutter of the secondary chamber, since it is acted upon by a return spring, mounted on the axis of the primary chamber.

When moving the lever 4 drive axis of the primary chamber the leash of the lever of the primary chamber at first freely moves in the groove of the backstage 25 (thus, only the shutter of the primary chamber opens) and after about 2/3 of its stroke, the leash begins to turn it. backstage 25 the secondary damper actuator opens the secondary throttle. When the gas is released, the springs return the entire lever system to its original position.

Carburetor Care

Carburetor care includes:

1. External inspection to remove dirt and detect traces of fuel leakage.

2. Periodic cleaning and flushing of the carburetor.

3. Checking the fuel level in the carburetor float chamber and, if necessary, adjusting it (simultaneously check the tightness of the fuel valve).

4. Checking the throughput of jets.

5. Checking the tightness of the connections between the carburetor assemblies, the health of the gaskets, the density of the plugs.

6. Checking the gap between the air and throttle valves and their housings.

7. Checking the correct operation of the secondary throttle opening mechanism and the absence of jamming in the joint operation of the primary and secondary throttle valves.

8. Checking the operation of the accelerator pump.

9. Checking and, if necessary, adjusting the throttle opening angle with the choke valve fully closed.

10. Adjustment of low idle speed of the engine.

Periodic cleaning and flushing of the carburetor is carried out during seasonal maintenance, as well as in cases of increased gasoline consumption, a sharp decrease in power in transient conditions and unstable operation at low idle speeds.

The float and mixing chambers, the cover of the float chamber, diffusers, air, fuel and emulsion jets and channels in the housings are subjected to cleaning. To perform this work, the carburetor must be completely disassembled.

Carburetor disassembly should be done on a clean, specially equipped workbench, serviceable and well-fitted wrenches and screwdrivers (careful not to damage the gaskets). If the carburetor worked on leaded gasoline, then before disassembling it should be lowered into kerosene for 10-20 minutes.

After disassembly, all parts of the carburetor must be thoroughly washed and cleaned of dirt. Flushing is carried out in unleaded gasoline or in hot water (at a temperature of at least 80 ° C).

Channels and jets should be cleaned after flushing with compressed air. It is impossible to clean the jets and other calibrated holes with wire, drills and other metal objects, as this leads to an increase in the throughput of the jets and excessive consumption of gasoline.

The jets are checked on special devices by measuring their throughput (in cm 3 / min) under a water pressure of 1000 ± 2 mm at a temperature of 20 ° C or by measuring them with calibers.

The economizer valve must be sealed. It is allowed to fall no more than four drops per minute under the pressure of a water column 1000 ± 2 mm high, compressing the valve spring. The timing of the economizer valve is adjusted at wide open throttles. The valve should be fully engaged with a gap between the accelerator pump drive bar and the adjusting nut equal to 1.5-2 mm.

It is necessary that the throttle and air dampers turn completely freely, without jamming, and tightly cover the channels. Clearances are allowed: no more than 0.06 mm for the primary throttle and 0.2 mm for the air. A gap between the secondary throttle valve and the body is not allowed.

Checking the density of the throttle valves is carried out on a special device that creates a vacuum under the dampers equal to 570 mm Hg. Art. The drop in vacuum should be no more than 15 mm Hg. Art. for the primary damper and not more than 20 mm Hg. Art. for the secondary. This corresponds to the passage of air, respectively, about 2 and 2.3 kg/h.

You should also check the performance of the accelerator pump, which should be at least 12 cm 3 for 10 full strokes of the piston (at a measurement rate of 20 strokes per minute). If the pump performance is less than the specified one, this means that the tightness of the pump valves is broken, the sprayer is clogged, or the piston and pump well are worn out. To eliminate the defect, rinse and blow the sprayer and valve seats or pick up a new one to the well. It is necessary to pay attention to the sensitivity of the accelerator pump. The fuel supply must begin simultaneously with the start of the damper stroke. A delay of no more than 5 0 is allowed.

Checking the throttle opening value at the time of starting a cold engine is carried out by measuring the gap between the throttle edge and the wall of the mixing chamber. To do this, completely close the air damper; at the same time, the throttle valve of the primary chamber by a system of levers and rods should open slightly at an angle of 18-21 °, which corresponds to a gap between the throttle edge and the chamber wall of 1.8 mm. If the adjustment is violated, the specified size is restored by bending the connecting rod.

The fuel level in the float chamber is checked by placing the car on a horizontal platform, when the engine is running at a low crankshaft speed in idle mode for 5 minutes or, if the carburetor is removed from the engine, on a special installation. The fuel level should be within 18.5-20.5 mm from the lower plane of the float chamber connector. The level is measured through the viewing window of the carburetor. If the level is outside the specified limits, then it must be adjusted. For this purpose, the tongue of the float bracket is bent. By preliminary bending this tongue, the float is installed so that it is located at a distance of 40-41 mm from the connector plane. At the same time, the float stroke is adjusted with another tongue so that the stroke of the valve needle is approximately 1.5-2 mm.

If the fuel level cannot be adjusted, then you should check the tightness of the float and the fuel valve, and also check the mass (weight) of the float, which should be 12.6-14 g.

Adjustment of the low frequency of the engine crankshaft in idle mode is carried out with a stop screw 5 limiting the closing of the throttle valve, and a screw 2 changing the composition of the mixture. When turning the screw 2 the mixture is leaner, and when unscrewing it is enriched.

Adjustment of the low speed should be carried out with a well-heated engine (coolant temperature 85-90 0 C), with a working ignition system. Particular attention should be paid to the serviceability of the spark plugs and the correct gap between their electrodes, as well as the correct gap between the breaker contacts.

Before starting the adjustment, tighten the screw 2 until it stops, but not too tight, and then back it off 2.5 turns to pre-enrich the mixture. After that, start the engine and install with a stop screw 5 small throttle opening, at which the engine runs quite stably. Then, turning the adjusting screw 2 , lean the mixture so that the engine runs stably (about 600 rpm), does not stop after a sharp opening and closing of the throttle and starts well with the starter.

Bibliography

1. Device, maintenance and repair of cars: Textbook / Yu.I. Borovskikh, Yu.V. Buralev-M.: Higher school; Academy Publishing Center”, 1997.-528s.: ill.

2. Roitman B. A., Suvorov Yu. B., Sukovitsin V. I. Vehicle safety in operation. -M.: Transport, 1987. - 207 p.

3. Talitsky I. I., Chushchev V. A., Shcherbinin Yu. F. Traffic safety in road transport: a reference book. - M.: Transport, 1988. - 158 p.

4. Shukhman Yu. I. Fundamentals of driving and traffic safety. -M .: CJSC "KZHI" "Behind the wheel", 2004.-160s.: Ill.

5. Konoplyanko V. I. Fundamentals of road safety. - M.: DOSAAF, 1978. - 128 p.

6. Rodichev V.A. Trucks: Proc. For the beginning prof. Education.-2-E ed., Ster.- M.: ProfObrIzdat, 2002.-256s

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