Mixture quality screw on carburetor

Most modern gasoline cars are equipped with fuel injection systems, but before they gained dominance, all cars were equipped with carburetor systems. For this system to work correctly, the carburetor settings must be performed flawlessly. High-quality carburetor adjustment will reduce fuel consumption, make the engine run smoothly at idle, reduce the emission of harmful substances into the atmosphere and increase the overall engine life.

Most domestic cars have a carburetor system, and the question of how to adjust the carburetor will not lose its relevance for a long time. Many owners of rare old foreign cars also face the problem of how to adjust the carburetor. Since the principle of operation of carburetors around the world is no different, the algorithm of work will be the same.

The carburetor is the main component of the fuel system of any carburetor car. This is where air and fuel mix to form a fuel mixture that enters the engine's combustion chambers. A properly adjusted carburetor produces a fuel mixture in the required proportions. Such a mixture will not detonate in the cylinders, which will increase the life of your engine.

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1↑ Topic from PATRIOT 03/25/2013 14:32:03

PATRIOT
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Topic: Carburetor adjustment (mixture quality) for beginners!

I think once again it will be useful for beginners to read about adjusting the quality of the mixture, and even the carburetor itself. As already noted, the quality of the mixture at different crankshaft speeds is adjusted differently:

for small ones, use the “quality screw” of the idle speed system;

at medium - with a throttle needle;

at maximum - with the main fuel jet.

Before proceeding with the adjustment, it is necessary to determine the quality of the mixture in various modes by external signs of engine operation. Signs of working on a lean mixture are popping sounds in the carburetor, a drop in power (deterioration of throttle response, drop in maximum speed). Signs of running on a rich mixture are black smoke from the exhaust at maximum speed, popping noises in the muffler, and poor engine response.

In addition, the quality of the mixture can be determined by the color of the spark plug insulator:

with normal mixture quality, the color of the insulator is brown,

with a lean mixture, the color of the insulator is whitish-gray or light brown,

with a rich mixture, the color of the insulator is dark brown or black.

Carburetors are adjusted on a warm engine. If the carburetor is adjusted on a cold engine, then when the engine warms up, it will be disrupted, since the volatility of gasoline in contact with heated parts will change and the quality of the mixture will change accordingly.

The left and right carburetors are adjusted separately. To do this, place the motorcycle on a stand and start the engine (to facilitate starting on two cylinders). On the carburetor cylinder that is not being adjusted, remove the tip from the spark plug and short it to ground. If the tip of the spark plug is not connected to ground, the process of spark formation in a working cylinder will be difficult, especially with discharged batteries. In this case, the engine will operate at an increased speed and the carburetor adjustment will be inaccurate. Next, you need to make sure that there is a gap between the cable sheath and the stop on the carburetor. If there is no gap, ensure it by screwing in the stop.

Then adjust the mixture quality at idle. To do this, you need to unlock the idle quality and quantity screws. Screw the “quality screw” 22 (Fig. 5.4) all the way and use the “quantity screw” to set the minimum stable crankshaft speed. Then slowly turn out the quality screw. In this case, the over-enriched mixture begins to become leaner, but will still be rich. When the mixture composition corresponds to the norm, the rotation speed will increase.

As you further turn out the quality screw, the mixture will become leaner, the rotation speed will not increase, and if the mixture becomes too lean, popping noises will appear in the carburetor, so during the adjustment process, turn the quality screw out until the rotation speed increases. It is difficult to determine from the first time at what position of the quality screw the increase in rotation speed stops, so it is advisable to repeat the adjustment operation 2 - 3 times. Turning out the screw, notice when the increase in rotation speed stops. Having finally established the required position, lock the screw. After adjusting the quality of the mixture at idle using the quantity screw, reduce the engine crankshaft speed to the minimum stable speed. After one carburetor has been adjusted, the second one must be adjusted in the same way. Then, with the engine idling, you must alternately remove the caps from the spark plugs of the left and right cylinders and check by ear whether the crankshaft rotation speeds are the same when operating on the left and right cylinders. If the frequencies are not the same, then you need to use the quantity screw, increasing or decreasing the rotation speed, to restore the balance.

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After adjusting the quality of the mixture at idle, adjust the quality of the mixture at average speed. But first it is necessary to check the quality of the mixture by sharply “opening” the throttle. If at the same time popping sounds appear in the carburetor or “dips” in engine operation (flashes in the cylinder stop; at the same time, if the throttle is “opened” smoothly, the engine gradually picks up speed), then the mixture is lean. If the engine speed begins to increase slowly, the mixture is rich, if quickly, the quality of the mixture is normal.

The quality of the mixture at average speed is regulated by the throttle needle. If the mixture is lean, you need to move the needle lock to a lower groove so that the needle rises. If the mixture is rich, you need to lower the needle, move the lock to a higher groove.

Basic faults

In order to make adjustments, you need to know several typical faults. Since this unit is responsible for dynamic characteristics, breakdowns include:

Problems starting the engine, engine sneezing.
Jerks, jerking, frequent failures on the accelerator pedal.
Lack of overclocking options.
Increased fuel consumption.

So, if while operating your car you were able to detect one or more faults from this list, then the part needs repair.

You need to know that the maximum adjustment of the DAAZ 2107 1107010 carburetor is possible only with the unit removed. The process does not involve cleaning this device with lint or woolen rags. You also won’t need any wires to clean the jets.

When making adjustments yourself, you must first remove the cover from the assembly. Then you can proceed to adjusting the float chamber. It's comfortable.

Adjusting and tuning the carburetor: main steps

Most domestic cars have a carburetor system, and the question of how to adjust the carburetor will not lose its relevance for a long time. Many owners of rare old foreign cars also face the problem of how to adjust the carburetor. Since the principle of operation of carburetors around the world is no different, the algorithm of work will be the same.

Carburetors used on the VAZ-2107, or those whose use is possible

Fundamentally, all these devices can be divided into only two groups.
The former trace their history back to the Weber carburetor modified for the first VAZ cars. This is a structural division of the Italian company Magneti Marelli, which works closely with the FIAT concern. Namely, this is where all the VAZ classics came from. After significant reconstruction, the family received the generic name “Ozone”. They were installed on the VAZ-2107 on the assembly line. The second direction consists of more advanced, yet simple, French Solex devices, produced in Russia by the same factories for the next generations of VAZ cars. The change in the vector of development had an effect, when the first front-wheel drive cars were developed with the participation of German and French companies. As more economical, these carburetors were also adapted to the families of Tolyatti cars with a longitudinal engine. For VAZ-2107 with 1.5 and 1.6 liter model 21053-1107010-20 ; the car will become more economical, although engine output will decrease in some modes. But this is a completely different carburetor; it was not used on production cars, and its adjustment is completely different.

2107-1107010 — the carburetor is equipped with a number of parts for working with the electronic forced idle system (EFI). Configured for the operation of a vacuum ignition timing regulator.
2107-1107010-10. The same device, but much simpler, does not have a vacuum supply tube to the regulator and is not equipped with a valve and switch for the EPHH system.
2107-1107010-20. The most common modification. Controls a vacuum regulator, not intended to work with capricious EPHH.

All these models are structurally very similar, but differ in a number of calibration data; accordingly, the difference in adjustments is mainly numerical in nature.

How to adjust the carburetor and when to do it

Do-it-yourself carburetor adjustment is done after using low-quality gasoline or when engine operation is no longer stable. For prevention, the manufacturer recommends flushing the carburetor with a special compound every 6-7 thousand kilometers.

Possible malfunctions in the carburetor:

Fuel leaks on the carburetor. In this case, you need to measure the fuel pressure. This is done using a special pressure gauge. The operating instructions will tell you what the pressure should be. Typically it ranges from 0.2 to 0.3 atmospheres. If the pressure is normal, the problem is in the float chamber and the fuel level needs to be adjusted;
Carbon deposits on spark plugs with the smell of gasoline. This clearly indicates a problem with adjusting the carburetor floats or a burnt valve;
Rough engine idling may not only be due to the carburetor. This often happens due to incorrect adjustment of the throttle cable. To check, you need to disconnect the cable and turn the valve manually.

Before you adjust the carburetor correctly, you need to clean it thoroughly. It is recommended to use special liquids for cleaning. The jets cannot be cleaned with toothpicks or needles. Damage to the jets will lead to calibration failure. If the holes cannot be cleaned with aerosols, you can carefully clean them with a soft wire. When cleaning, do not use rags. Threads can clog the holes, which will lead to malfunction of the carburetor. If the aerosol does not remove all contaminants the first time, you need to repeat the procedure.

Engine operation before and after adjustment

Preventive and regulatory measures must be carried out in a certain sequence.

Carburetor maintenance steps:

external cleaning of the device;
visual inspection of the unit, which may reveal some problems;
dismantling and cleaning the mesh filter element (this must be done every 60 thousand mileage).
cleaning air jets;
if necessary: setting the XX, PU and float assembly.

As a result of such simple measures, the engine will start easily, there will be no interruptions in its operation, the car’s dynamic characteristics will improve, no dark smoke will be visible from the exhaust pipe, fuel consumption will return to normal, and the engine noise will decrease.

Of course, many types of car maintenance work are not so easy to do at home. However, this does not apply to the system for preparing and supplying the fuel-air mixture.

Knowing what the carburetor diagram looks like, the principle of its operation, as well as the installation standards for the main parameters, each car owner of a car on which the DAAZ 2022 is installed is able to carry out most of the work on adjusting and repairing the device independently. This allows you to save material resources and time that you have to spend on trips to the service.

Setting up the float mechanism

The level of the fuel mixture in the float chamber is directly related to its quality. At an increased level, the mixture will turn out to be lean, which will negatively affect gasoline consumption and increase toxicity. Without adjusting the floats, the question of how to adjust the carburetor cannot be solved. The process of adjusting the floats includes the following operations:

Adjusting the floats in relation to the lid and walls of the fuel chamber. If deformation of the float fixing bracket is noticed, it should be aligned manually;
We adjust the bracket with the needle valve closed;
We adjust with the float retracted and the valve open; the distance between the float and the valve should in this case be set to about 15 millimeters.

Adjusting the accelerator pump

Accelerator pump metering systems

The main task of the accelerator pump is to supply a smooth and powerful stream of gasoline through the open throttle valve of the carburetor (dripping and sluggish streams are not allowed). The stream of gasoline should enter directly into the manifold, without touching the walls of the diffuser and throttle valve.

Flowing of gasoline down the diffuser stack or throttle valve is not allowed, since the car will become very blunt and jerky when you press the gas sharply.

An accelerator pump with two spouts must be installed in different chambers. You can insert two spouts into the primary chamber - this can increase the agility of the car, but also lead to excessive “overflow”.

Setting the fuel mixture supply

The carburetor control screws will help you figure out this setting. Before performing this procedure, you should know that the screws have a plastic factory press-on that limits the rotation of the screws (from 50 to 70 degrees). If turning in this range does not bring results, you need to break the press-on and turn the screws as much as necessary. Before setting the position of the screws, you should warm up the car engine to operating temperature.

To adjust the idle speed of the carburetor, you need to turn out the quantity screw and the mixture quality screw a few turns and, turning them, listen to the operation of the engine. When the engine starts to run smoothly, the carburetor idle adjustment is complete.

Disassembling and cleaning the unit

Considering that the amount of impurities in our gasoline is simply off scale, cleaning the VAZ 2107 carburetor turns into a necessary procedure. It can be carried out without dismantling and disassembling, or it can be done with complete disassembly of the device.

Cleaning without dismantling, video.

Many car owners periodically treat the carburetor with special cleaning agents (carbocleaners). These aerosols do a good job of removing deposits in gaps, unless, of course, they are perennial “growths.”

The engine must be turned off and cool before starting work;
Remove the air filter housing;
Using a wrench, unscrew the idle speed solenoid valve on the carburetor;
Use a carb cleaner to treat the carburetor: external surfaces, jet channels (through a thin tube), chambers, air dampers, etc., as far as you can get;
Leave for 10 minutes for the aerosol to dissolve deposits;
Run the engine for a couple of minutes. A stream of gasoline will wash away the residue;
If necessary, repeat the procedure, first waiting until the engine cools down.

If such cleaning does not produce results after twice use, the carburetor will have to be removed and cleaned “like an adult”, with disassembly.

Cleaning with removal, video.

How to remove the carburetor is already clear. Now the sequence of its disassembly:

Remove the top cover by unscrewing the five mounting screws;
Unscrew the jets and remove the emulsion tubes;
Remove the accelerator pump nozzle - unscrew it, pry it off with a screwdriver and remove it;
Remove the seal located under the valve;
Remove the diffusers from the chambers using pliers or carefully knock them out with the handle of a screwdriver;
Unscrew and remove the accelerator pump screw;
Unscrew the adapter system nozzle holder and remove the nozzle itself;
Unscrew and remove the idle fuel jet;
Remove the accelerator pump cover: unscrew the 4 screws in the corners, remove the cover and the pump itself (diaphragm, pusher, spring);
Remove the return spring from the pneumatic drive lever, then the rod clamp, after which remove the spring from the throttle valve drive lever;
Remove the pneumatic drive by unscrewing the fasteners;
Unscrew the 2 screws that secure the lower part of the carburetor to the body, remove the lower part; Remove the economizer and economizer microswitch with bracket;
Unscrew the screws for adjusting the quantity and quality of the mixture.

This completes the disassembly of the carburetor. After this, you can start cleaning. The parts and body of the carburetor, including the jets, can be washed with kerosene, the seats of the jets and the jets themselves can be blown out with a compressor. It is advisable not to clean the jets with wire; it can damage the holes and then the jet will have to be replaced.

When the layers are washed off the metal, you can inspect it for corrosion, wear and defects. All parts that show signs of wear must be replaced with new ones. The carburetor is assembled in the reverse order, then adjustments are made and you can put it in place.

Adjusting the carburetor draft

Before you begin adjusting the rods, you should remove the air filter cover so that nothing interferes with the process. First, using a caliper, measure the distance between the rod tips. According to factory parameters, it should be 80 millimeters. To adjust the length of the rods, you need to loosen their clamps.

Checking the strainer should be carried out when there is fuel in the float chamber. This will help you see if the shutoff valve is closing completely. After examining the valve, you need to clean and dry it. Problems with loss of power and engine failures occur due to obstructed fuel supply. This is another reason to thoroughly flush the carburetor.

The tightness of the shut-off needle can be checked using a rubber bulb, while listening for air leaks. If they are present, it is time to change the needle.

Problems with the DAAZ 2107 carburetor

Despite the fact that the device is reliable and durable, units that are more than 30 years old are also in use today. During such a period of use, the likelihood that the car owner will encounter various kinds of problems is quite high.

What malfunctions are typical for Dimitrovgrad-made carburetors:

The engine stalls when you press the gas

At the moment of start or when idling, the power unit may stall when the driver smoothly presses the pedal.

Why does this happen:

The holes in the transition system of chamber 1 may become clogged. They need to be blown out or treated with a cleaner.
The accelerator pump is broken. It is replaced or repaired.

It is also possible that when moving while gas is supplied, the engine jerks and may stop. To prevent this, you urgently need to press the pedal again.

What does this mean:

The channels, jets or emulsion well are clogged. The defect can be eliminated by cleaning the elements.
The nozzle of the dosing system of chamber 1 is not screwed in completely. It needs to be wrapped.
The jets are not selected correctly.
The fuel level in the float chamber is insufficient, which is regulated by setting the float and valve.
The filter installed at the inlet is dirty. It needs to be dismantled and cleaned.
Poor condition of sealing elements that need to be replaced.

The ignition system may also be faulty.

Pouring gasoline

This problem is encountered quite often. Usually it lies in a malfunction of the metering units or the vehicle’s fuel system.

Causes of problems:

malfunction or leakage of the needle valve;
leakage or breakdown of the float;
the float touches the walls when moving around the chamber;
the fuel level in the float chamber is exceeded;
the jets supplying air are clogged;
fuel pump failure.

Knowing the design of the carburetor, it is not difficult to find the source of the problem.

Shoots

The power unit may shoot into the carburetor. Such pops can be heard both at start and when moving at speed. This leads to high fuel consumption, engine overheating, unstable idling, and also to the fact that the engine cannot develop full power. Shooting indicates improper adjustment of the fuel-air mixture preparation and gas distribution system.

Gasoline is not supplied

If fuel does not flow into the carburetor, there can be many reasons.

Main sources of problems:

fuel filter contamination;
ice formation in the gas pipeline;
leaks at fuel line connections;
interference in the hose that comes from the gas tank;
fuel pump failure;
contamination of the carburetor filter element.

The second camera does not work

In carburetors with two chambers, it is possible to increase the efficiency of the power unit while maintaining excellent power parameters. However, the 2nd compartment often fails.

The malfunction may be related to:

flooding due to contamination of fuel channels;
incorrect clearance settings;
malfunction of the throttle valve drive;
poor condition of the pneumatic drive diaphragm;

failure of any elements: jets, diffuser, economizer XX, etc.

Accelerator pump does not work

Problems in the functioning of this unit lead to the fact that gasoline does not flow or is supplied under the wrong pressure, resulting in difficulties with acceleration. As a rule, the reason for the lack of fuel flow is a clogged fuel nozzle of the accelerator unit or a ball sticking to the check valve bushing. If the jet does not have enough pressure, you should pay attention to the condition of the ball and its position, as well as the leakage of the diaphragm connection, which is located between the top cover and the body. To fix the problem, you need to clean the components and evaluate their condition.

How to properly adjust a Solex carburetor

There are still many representatives of VAZ classics driving along the roads. Many of these cars have Solex carburetors under the hood. This carburetor is more economical and is capable of producing a higher quality mixture of fuel and air. For smooth operation of the engine, this carburetor must be properly tuned and adjusted. The class of carburetor masters is gradually dying out, so many people have to do the carburetor adjustments themselves.

A little about Solex and its design

Carburetors have long been replaced by injection systems. But they are still found in cars driving on Russian roads - in old foreign cars and VAZs produced 20 years ago or more. Before the release of VAZs with injection engines, a number of models were equipped with a Solex carburetor, and interest in it does not dry up.

Adjustment of the Solex carburetor installed on the engine is usually done at a car service center. But, if you wish, you can adjust the device yourself - adjust the quality of the fuel-air mixture (FA) and adjust the Solex float chamber. Solex prepares the fuel assembly and supplies it to the engine in the required volume.

How Solex works:

On a note! The operation of the Solex carburetor uses one diffuser chamber or two - this depends on the operating mode of the car engine.

How to set the ideal settings yourself

To work, you will need the usual set of tools that are found in almost every garage. To eliminate fuel overflows, you need to correctly set the float in the chamber. This operation can be done using a special template. Experts recommend not using this template, since the number and thickness of gaskets in carburetors do not always match. Fans of various improvements often replace factory gaskets with better ones. It happens that the factory settings of the template do not suit everyone. Although Solex carburetors are the same, the fuel pump can deliver gasoline differently. A lot also depends on whether the return line is plugged, so specialists use a different method.

The mixture quality adjusting screw is tightened by hand until the end;
Next, unscrew it back five turns;
Turn on the engine, remove the choke and use the mixture screw to bring the engine speed to 750 rpm;
By turning the quality screw, we bring the engine speed to the maximum;
Using the quantity screw, reduce the speed to 800 rpm;
We tighten the quality screw a little until instability appears;
We unscrew the same screw back one turn;
We turn the quantity screw until the idle speed reaches 800 rpm (in winter they can be raised to 900).

It is worth remembering that adjusting the carburetor not only eliminates floating engine speeds. A well-tuned carburetor will consume a minimum amount of fuel at stable idle speeds.

Various problems may arise with this adjustment.

It happens that when unscrewing the quantity and quality screws, the engine practically does not react. This happens when a large stream of gasoline flows from the idle hole and the screw is unable to influence it. It is possible that the valve is poorly closed or the jet is deformed. It happens that when replacing jets, they mistakenly choose a larger diameter than required. The plug may be loose. It is worth conducting a thorough inspection of all carburetor elements, this will help avoid such problems. When cleaning, the jets must not be cleaned using abrasives.

If the solenoid valve malfunctions, unscrew it and check for deformation. The mounting hole may also be deformed. If the thread of the mounting hole is torn off, you will have to replace the carburetor cap with a new one. If no defects are found, simply lubricate the O-ring before screwing in the nozzle.

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You can determine whether the carburetor needs adjustment by the engine's response to pressing the gas pedal. An engine receiving a balanced fuel mixture responds to pedal pressure without hesitation, in a split second. The speed should be smooth at idle. There should be no jerks or failures. If the engine runs smoothly at idle, but when you press the accelerator it begins to act up, you need to tighten the quality screw, enriching the mixture.

The quality screw directly affects CO emissions into the atmosphere. Drivers are familiar with the situation when, before going for a scheduled inspection, they need to tighten the quality screw. The emissions become smaller and the car easily passes inspection, after which the position of the quality screw returns to its place. Some people are perplexed why their neighbor’s car consumes less fuel, although both have identical models. It's all about the settings and adjustments of the quality screw.

If the car responds to pressing the gas pedal late, the problem is in the accelerator pump. You can replace it, or change only the spout. When it comes to the spout, the fuel mixture is supplied over-enriched. The problem is solved by replacing the spout. If you decide to install a spout of a different diameter, do not forget to select the appropriate jet for it.

Setting up a carburetor is a rather complicated procedure. Don't expect everything to work out the first time. It may take a couple of weeks to complete the full cycle of eliminating all deficiencies. It is better to listen to the engine, quickly respond to the slightest interruptions in its operation and carry out regular carburetor flushing. The main thing when washing is not to use nameless Chinese-made cleaning products. And if you refuel with high-quality fuel, the carburetor will thank you for years of trouble-free operation.

Subtleties of adjustment with removal

When thinking about removing the carburetor, you need to take into account that this adjustment procedure is much more complicated. Here you will need accurate calibration data, which may differ for different cars. You also cannot do without checking the functionality of all components of the device.

Adjustment usually begins with troubleshooting.

A fairly common problem is when popping noises are heard at the outlet of the exhaust system, and when the popping appears, the tachometer twitches. This indicates problems with the idle speed - it is not adjusted or clogged.

What to do in the latter case? The defect lies in a clogged channel or nozzle that allows fuel to pass through.

How to fix the defect:

The jet is unscrewed, paying attention to the holes, which should be round;
After removing the head of the part, it is easy to clean the pusher and the hole in the head itself;
If the rubber band that fits over the jet is torn, it will need to be replaced.

The efficiency of the jet affects how the car and the carburetor itself operate.
If the setting is carried out correctly, this is easy to check - with the jet removed, the engine will quickly stall after starting. At the same time, it must be taken into account that the settings do not always correspond to the standard, since small deviations in dimensions cannot be ruled out during the production of parts.

Variations in parameters of up to 5% are allowed, which means the need for the correct selection of jets. In order for the carburetor jets to be adjusted correctly, the volume of the power unit is taken into account.

Basic manipulations:

Using a wire, you need to fix the throttle valve of the second chamber so that it does not interfere with the adjustment.
First you need to work with the fuel nozzle, replacing the standard device with a model of lower performance - with a decrease in the number of markings, the throughput is reduced. Replacement is carried out until twitching occurs when moving, or dips occur when the damper is open. At this point, the nozzle is removed, screwing in the previous one, where the performance was slightly higher.
If dips begin to appear during the start of the car, you will need to enrich the mixture by additionally adjusting the idle speed.

If you want to know how to improve the performance and efficiency of the machine, you need to remember that in the second chamber you should not use a main jet with a lower throughput. After all, because of this, the process of accelerating the car will be reduced, therefore, there will be no savings.

The process of adjusting the carburetor also includes monitoring the level of the float chamber, checking the functionality of the accelerator pump and other structural elements. When working independently, it is recommended to watch the video to avoid mistakes.

Jets and accelerator pump

A nozzle (injector) is a device for supplying fuel in a certain amount. The engine draws in air through the opening of a large diffuser. At the same time, fuel is dosed through the nozzle. The amount of air sucked in through the diffuser, as well as the amount of gasoline drawn in, depends on the engine displacement. Because of this, on engines with large volumes, carburetors with small jets are installed.

In order for the jet to produce a normal fuel assembly, not lean, it is necessary to find a carburetor that was initially designed for a certain engine volume or as close as possible to it. First, select the fuel and then the air jet. They are selected for the first camera, then the second camera is configured.

The accelerator pump is necessary to supply additional fuel when the throttle is opened, this provides more efficient acceleration. The pump operates through a special cam mechanism. On engines with Solex, you need to install the largest possible cam for the accelerator pump.

How to adjust the gasoline level

Setting up the carburetor begins with setting the gasoline level in the float chambers. It is recommended to align it along the floats to the carburetor cap. For this purpose, you can use a template, but practice shows that this method produces errors, especially when excess fuel gets into the carburetor.

How to accurately adjust the fuel level in the carburetor and adjust its floats:

If the level after adjustment is still different from the norm, you have to repeat the adjustment. Please note that you cannot adjust the level with the engine turned off and manual pumping - if the engine is started, there will still be overflow in the carburetor. This especially applies to engines with a blocked return flow.

Injection system with multiple carburetors

We can talk about tuning carburetor injection systems on internal combustion engines, taking into account extreme solutions. These include the installation and adjustment of several carburetors (from 2 to 4). This scheme, especially when installing a separate carburetor for each cylinder, can provide a significant increase in power and torque. The disadvantage is the complexity of installation and proper configuration of such an engine power system.

The reason lies in the fact that there are no completely identical carburetors. The slightest errors in setting up just one device can deprive the motor of the expected benefits. In practice, the implementation of such a forcing solution involves many alterations, modifications and financial costs. For an ordinary civilian car, the feasibility of such modifications is questionable, although this tuning method has become widespread in motorsport.

Adjusting the idle speed of a car engine with a carburetor 2108, 21081, 21083 Solex

Tools needed to adjust idle speed

— Tachometer To determine the crankshaft speed.

You can use the panel built into the instrument panel (on vehicles equipped with a tachometer). You can connect a separate device (tachometer, auto tester or multimeter operating in tachometer mode). It is better to use a separately connected device since the engine crankshaft rotation speed will be more accurately determined, and therefore the idle speed adjustment will be performed more efficiently.

Adjustment by ear is also possible, but it requires some experience in car repair.

— Slotted screwdriver For rotating the “quality” screw of the fuel mixture. Blade width 3 mm.

1. Warm up the engine to operating temperature (85-90°).

2. Push in the carburetor air damper drive handle (“choke”) until it stops.

The air damper must be fully open.

The air damper of the carburetor 2108, 21081, 21083 Solex is completely open

3. With the engine turned off, connect the tachometer (multimeter, auto tester).

If there is no device, then skip this point. The positive terminal of the device is to terminal “K” of the ignition coil, minus to the “ground” of the car (body, engine, minus battery).

The procedure for connecting a tachometer (autotester) to a car’s ignition coil

Before connecting, read and follow the instructions for your device.

4. Start the engine, turn on the high beam headlights and the heater.

To create a load on the network.

Recommended idle speed for engines equipped with Solex carburetors 2108, 21081, 21083 750 - 800 rpm . We achieve stable engine operation within the specified interval. We simply rotate the “amount” screw of the fuel mixture and set the crankshaft speed to 750 - 800 rpm.

Adjusting screw for the “amount” of fuel mixture of the carburetor 2108, 21081, 21083 Solex

If it is not possible to set the required rotation speed using the “quantity” screw alone, then you will have to make adjustments by adjusting the “quality” screw of the fuel mixture. Perhaps there is still a plastic factory plug on it, it needs to be removed. We pierce it with an awl and pull it out using a metal hook or screw a self-tapping screw into it and pull it out. We carry out the adjustment in three steps; if we do not achieve the desired result, we repeat it once or twice more. Before carrying out it, it is advisable to check the correct setting of the ignition timing and the serviceability of the high-voltage wires. spark plugs, no “suction” of foreign air into the carburetor.

1. Using a slotted screwdriver, rotate the fuel mixture “quality” screw and achieve the maximum engine crankshaft speed.

We rotate both to the right and to the left until we find the desired position of the screw with the maximum frequency. We determine it by the tachometer or by ear.

Screw of the “quality” of the fuel mixture of the 2108 Solex carburetor

2. Turn the fuel mixture “amount” screw and set it to 900 rpm.

By turning the screw (clockwise), we open the throttle valve of the first chamber slightly and the speed increases; by turning the screw (counterclockwise), we close the throttle valve and the speed drops. Therefore, again, we are looking for the desired position of the “quantity” screw at which the speed will correspond to this value (900 rpm).

3. Tighten the “quality” screw and set the required 800 rpm.

If necessary, repeat the adjustment.

If another carburetor is installed instead of the old one, or the “quality” screw has been changed, or the carburetor has been disassembled and assembled due to repairs, then before adjusting, screw the “quality” screw all the way (clockwise), and then turn it out 3 - 4 turns and start adjustment.

— After completing the adjustment, press the gas pedal; the engine should increase the crankshaft speed without interruption and not stall when it is released. If there is a “failure,” adjust again or slightly enrich the mixture by turning the mixture “quality” screw. It is allowed to increase the idle speed to 900 rpm.

— When the mixture “quality” screw is rotated clockwise, the CO content in the engine exhaust decreases. In general, this adjustment on a working engine with a working ignition system allows you to achieve a CO content in the exhaust of no more than 1.5%.

— If by rotating the screws it is not possible to establish normal idle speeds and the engine is sluggish or does not respond at all to their rotation, then fuel enters the mixing chamber bypassing the idle system. This is possible due to the fact that the carburetor solenoid valve (or the plug installed in its place) is not fully screwed in and the fuel flows past the idle system fuel nozzle installed in the valve or plug. And the jet itself may have a hole larger than the required diameter. To check, remove the wire from the valve with the engine running - the engine should stall. If it doesn’t stall, check the solenoid valve. The valve is working properly, then we adjust the fuel level in the float chamber and check the needle valve. After all, we repeat the idle speed adjustment.

— In some cases, it makes sense to modify the carburetor idle system. See “Modification of the idle system of Solex and Ozone carburetors.”

Modification of the standard intake manifold

To tune the carburetor system, it is a good idea to equalize the length of the intake channels. To do this, part of the partition is cut off, which separates adjacent channels. This allows you to create a kind of cavity under the carburetor. In this cavity, the working mixture will mix much better, and this will happen without depending on the operating modes and the number of carburetor chambers involved. Only then will this mixture enter the intake channels.

The intake manifold itself must be placed on the cylinder head using pins. This is done so that their relative position is always the same. After installing the pins, it becomes necessary to join the channels in the intake manifold and the cylinder head in such a way that no ledges or other flaws appear at the junction. For best results, use a strip of paper that is thick enough. This paper must be pressed in turn both against the manifold flange and against the mating surface of the cylinder head. There will be prints on the paper corresponding to the channel holes, which can be used to easily identify places where the manifold and the block head do not match.

This method allows you to achieve positive results, which are manifested in improving the acceleration dynamics of a car with a carburetor without increasing fuel consumption. The second advantage is a noticeable expansion of the range of peak torque and maximum power of the internal combustion engine, and their increase is also observed.

How to adjust idle speed

Idle speed adjustment (IAC) is carried out when problems occur in the engine - if it does not start, stalls after starting and other problems. It is also recommended to perform IAC after replacing or repairing the carburetor.

For IAC you will need:

The optimal idle speed for engines with Solex is 750-800 rpm. Rotate the fuel mixture “amount” screw and set the crankshaft frequency indicated above. If you cannot set the desired speed, you will also have to adjust the “quality” screw of the fuel mixture.

On a note! There may be a plastic plug on the fuel mixture “quality” screw; before adjustment, it must be removed, pierced with an awl and pulled out with a hook or self-tapping screw.

XX adjustment is carried out three times. If there is no result, repeat it 2-3 more times. Before starting work, check whether the ignition is set correctly and the wiring is in good condition, and whether foreign air is being sucked into the carburetor.

Repeat the setup if necessary. If you are replacing an old carburetor with a new one, or you have disassembled or repaired it, then before you start adjusting, tighten the “quality” screw to the maximum, and then turn it out 3-4 turns.

Having completed the adjustment, step on the gas - the engine should increase the crankshaft rotation speed without failure, and when it is released, it should not stall. If there are “dips,” repeat the adjustment or turn the mixture “quality” screw. Increase the idle speed to 900 rpm. If you tighten the “quality” screw clockwise, the CO concentration is reduced to 1.5%.