Useful Tips

How to adjust the carburetor


The operation of each automobile engine depends on the quantity and quality of the air - fuel mixture prepared by a special device called a carburetor. All carburetor systems create a mixture and help to evenly distribute it across the cylinders. There are several ways to mix fuel with air flow. For example, there are membrane-needle carburetors, and there are float-operated ones. It is precisely this type of carburetors of the VAZ family that are manufactured by the Dimitrovograd Automobile Aggregate Plant (DAAZ).

Adjusting the VAZ 2107 carburetor is an important tool to keep the engine in working condition.

Before you adjust the carburetor, you need to know what type it is installed on the car. To do this, remember that:

  • If you have a vacuum ignition corrector, then this means that you have the latest type of VAZ 2103 or 2106 engine installed, and the carburetor modification 2107 is 1107010-20.
  • If your “seven” has a six-engined engine, but there is no installed vacuum corrector, then you have a carburetor modification 2107-1107010-10.

The main components of the carburetor to be adjusted:

In order to adjust the carburetor, you need to know the main signs of its malfunction. Since the carburetor is responsible for the accelerating dynamics of the car, then the following apply to them:

  • difficulty starting the engine, long “sneezing”,
  • all kinds of “jerks”, “jerking”, “dips” when you press the “gas” pedal,
  • sluggish ability to accelerate the car,
  • unexplained increase in gas mileage.

So, if your car has the corresponding "complaints", we proceed to adjust it.

Attention! The most competently possible to carry out the adjustment on the removed carburetor. Adjustment of the VAZ 2107 carburetor does not imply the use of fleecy and wool fabric, as well as various wires for cleaning the nozzles.

How to adjust the carburetor on your own on the VAZ 2107? When removing the carburetor cap, the float system is first adjusted, so convenient.

Float system adjustment

The free movement of the float varies between the following values: 6.5 mm on one side and 14 on the other. This can be adjusted using the test pattern by placing the camera vertically. In this case, the float slightly touches, but does not press on the ball of the valve.

In the event that the distance is less than 6.5 mm, then you need to slightly bend the tab of the valve (needle), which is shown in the figure with the letter "A".

After that, we adjust the degree of opening of the needle valve, which passes gasoline into the float chamber. When the float rises, the fuel supply decreases, when you press the “gas” pedal sharply and the throttle opens, the fuel consumption increases and the float drops.

Now we adjust the deflection of the float in the other direction. To do this, we take it as far as possible from the lid and check with a template whose thickness is 14 mm with a certain tolerance.

If the distance does not match, you need to bend the stop bracket bracket mounting the float and make it no more than 14 mm.

Now, after adjustment, the float’s free play is about 8 mm. Adjusting the VAZ 2107 carburetor also provides for checking incoming grids and fuel filters to maintain a full flow of fuel.

Purpose, principle of operation and fundamentals of the carburetor design

It is known that gasoline does not come into the cylinders of an internal combustion engine in its pure form, but what is technically called a fuel-air mixture. The process of preparing such a mixture is called carburetion, and the device for its preparation (mixing) is called a carburetor.

The principle of operation of the carburetor and the basics of its design are shown in the figure below.

The simplest carburetor contains two cameras: float and mixing.

The following processes occur in the float chamber:

  • Gasoline from the fuel tank is pumped by a gas pump through a filter into the float chamber,
  • The float rises and in a certain position by means of a needle valve blocks the flow of fuel,
  • After spending a certain amount of fuel, the level in the chamber decreases, the float drops and opens with the same valve the flow of a new portion of fuel into the chamber,
  • Then the process repeats.

At the top of the camera is balancing holewhose purpose is to maintain atmospheric pressure above the fuel.

As can be seen from the figure above, the float chamber is connected by a pipeline to another carburetor chamber: a mixing chamber, in which the process of formation of the air-fuel mixture and its supply to the working cylinders of the engine takes place.

How is the fuel sucked into the mixing chamber and sprayed in it? The fact is that, at the intake stroke, a vacuum is created in the mixing chamber, which sucks gas from the float chamber in the place where the atomizer is located. And so that the process takes place intensively, in this place is the neck (the bottleneck) of the device with the beautiful name "venturi».

The purpose of the venturi is quite simple: creating a pressure difference in the tapering and outlet parts of the pipeline. Often in the technical literature the tapering part of the chamber is called a diffuser, although strictly speaking, a diffuser is a part of the venturi that extends from the neck.

The change in pressure in a narrowing flow of liquid or gas is a direct consequence of Bernoulli's law, which relates pressure, the rate of flow of liquid or gas and the diameters of the pipelines. Simply put, at the point of narrowing, the pressure drops, and the flow rate increases, and the sprayer at this point is akin to the aerosol can.

A fundamental point in the operation of the carburetor is the accuracy of dosing the amount of fuel supplied to form a mixture. That is why the fuel in the atomizer comes through jet - a calibrated (i.e., made with high accuracy) hole at the outlet of the float chamber.

Located at the top of the camera choke serves to regulate the air supply to the chamber and thus facilitate starting the engine in cold weather (the air content in the mixture decreases, and gasoline, on the contrary, increases, compensating for its lack, which was formed due to condensation during cooling).

Throttle serves to quantitatively control the flow of air-fuel mixture into the cylinders: the more the shutter is open, the greater the amount of mixture enters the cylinders, increasing the speed, therefore, the power generated by the engine. Typically, the throttle through a cable traction is connected to the gas pedal (controlled by the driver).

Of course, the described design and the principle of operation only schematically reflect real processes. In practice, the design of the carburetor (most often containing two mixing chambers) ensures the operation of the engine in modes other than stationary (start, idle, acceleration, increased loads) and looks much more complicated.

So idling the throttle is closed and the vacuum in the spray area is not enough to form the required fuel mixture. But in the area of ​​the damper itself, the air mass has sufficient speed and sufficient vacuum is created to form the mixture. This is where the additional idle channel fits, equipped with fuel and air jets.

But what happens in acceleration mode. Due to the different density, the reaction to a sharp opening of the throttle valve is different for air masses and fuel: air enters faster. Therefore, additional fuel enrichment of the mixture is required, which is performed by accelerator pumps that are triggered by sharp depressions of the "gas" pedal.

With a sharp turn of the valve, the pump piston moves down through the linkage system and closes the check valve, and the pressure valve opens - an additional amount of fuel is injected into the mixing chamber.

Additional fuel enrichment is also required with fully open dampers in the mode of maximum (or close to) engine speed. Provides such a device mode called economizer - it consists of an additional channel for enriching the mixture with fuel in the channel of the atomizer, nozzle, and valve opening this additional channel.

In addition, in modern carburetors, a cold engine is started starting devicewhose main element is the air damper. The exhaust gases are burned by a recirculation system, and the toxic gases are removed from the crankcase by a ventilation system.

Features of carburetors "Ozone" and "Solex"

Before the production of injection engines, almost all Soviet and then Russian cars were equipped with carburetors produced by the Dmitrovograd auto-aggregate plant - DAAZ. For VAZ automobiles, which form the basis of the domestic fleet of vehicles, two-chamber Ozone carburetors have been produced since 1979, and Solex two-chamber carburetors have been produced since the mid-80s.

The main differences between these types of devices:

  • The design features of the Ozone float chamber include the installation of a carburetor on engines with a longitudinal arrangement (VAZ “classic”),
  • Ozone carburetors are less than Solex demanding on fuel quality due to the size of the jets. For the same reason, they have slightly higher fuel consumption and worse acceleration dynamics,
  • In the Solex design, simplifications justified by the operation of Ozone were carried out (for example, replacing the pneumatic throttle actuator with a mechanical one),
  • The Solex design provides an economizer of power modes, absent in Ozone.

Both types of carburetors (although Solex to a greater extent) are successfully used today.

Why cleaning and adjusting the carburetor

The factory settings of Solex / Ozone carburetors are designed for a certain quality of fuel and the average driving style of the driver, and are made on a specific engine. And if the car is operated in accordance with the manufacturer's instructions and on high-quality fuel, carburetor adjustments can be avoided for a sufficiently long time.

At the same time, the parameters of the content of harmful substances in the exhaust gases must be checked at a technical inspection with a frequency of from two years (if the car is not older than 7 years) to one year (which is more likely for cars with a carburetor engine).

The carburettor adjustment process is carried out by two screws and may well be performed independently (in any case, on a properly working carburetor). Recommended to see video at the end of the article.

The operations here are simple: by successively tightening the quality and quantity screws, they achieve stable and smooth operation of the engine in the range of 800-900 rpm (for winter time, the range of 900-1000 rpm is recommended).

When adjusting the carburetor yourself, you must remember that it is performed on a warm engine.

Another thing is when malfunctions occur that may be associated with the operation of the carburetor. Most often, this is a gas overflow in the float chamber and unstable idle speed. In the first case, it is necessary to adjust the position of the float (respectively, the needle valve) or replace the parts of the chamber, and in the second, it is most often not the carburetor that is to blame, but the “jamming” of the “gas” cable, which must be eliminated.

Sometimes carburetor malfunctions can occur in dips and jerks when driving or a sluggish set of power. However, similar symptoms can occur due to malfunctions of the ignition or fuel supply system, so before disassembling the carburetor, you must make sure that these systems are in good working order.

The quality of the fuel can also significantly affect the performance of the carburetor, therefore it is necessary to periodically (at least once every 50 thousand km, and with obviously bad fuel) clean it from contaminants and deposits. There are a lot of cleaning agents now, you just need to remember that the most aggressive ones can harm non-metallic parts (for example, diaphragm material).

To avoid tissue residues entering the carburetor, the removal of old fuel is usually done with a rubber bulb.

To clean the jets, it will usually suffice to blow them with compressed air, and only in advanced cases may need to be cleaned with a soft copper wire.

Adjustment of the carburetor after replacing it

Even with the exact make and model of the car, after replacing the old carburetor with a new one, you will need to configure it. The fact is that such engine characteristics, such as the degree of rarefaction in the cylinder at the intake stroke, change over time.

What can we say about the installation of a carburetor on an engine that is not properly designed for using another model of the device. In such cases, in addition to knowledge and experience, special equipment is often required: gas analyzers, strobe lights, measuring tools.

The adjustment is carried out in stages, and the settings are checked on various engine operating modes and are more likely for professionals than ordinary motorists.

Nevertheless, a number of adjustments to the regular carburetor can be made, which can make fuel consumption more economical and help to make the car more powerful in high-loaded modes and you can try it yourself.

In addition to the already mentioned adjustments in the quality and quantity of the fuel mixture and the fuel level in the float chamber, these can be the following operations:

  1. Adjustment of the air damper drive: when the “suction” handle is fully recessed, the damper should be fully open.
  2. Throttle Actuator Adjustment: With the throttle pedal depressed to the end, the damper must be fully open.
  3. Carburetor starting device adjustment: setting normalized clearances between the edges of the air and throttle valves and the walls of the mixing chamber.
  4. Correct installation of the electromagnetic valve (EMC): when removing the wires from the EMC (the needle valve closes the idle channel), the engine must stall.

Features of the settings and adjustments of carburetors depend on the specific model of the device and the parameters of the car engine, therefore, when working independently, you should first of all be guided by the manufacturer's technical documentation.

Getting started adjusting the starting device

Do-it-yourself tuning of the VAZ 2107 carburetor necessarily includes adjusting the starting device. Recall that it serves to confidently start a cold engine. For this, the mixture is doubled, tripled more saturated with fuel than with conventional hot engine power.

The starting device for carburetors of the 1107010 family is triggered at a frequency of 1,500 rpm, that is, at the recommended engine start frequency of a cold engine.

If you look at the carburetor from the side, you can clearly see the channel through which the vacuum is supplied from the space behind the throttle behind the diaphragm of the flap ajar:

If you remove the carburetor and look at it from the back, you can see the channel for supplying rarefaction of air:

If you disassemble the carburetor, you can see the details of this diaphragm starter:

Below is a schematic representation of the carburetor starting device of the 1107010 family:

We explain the mechanism of action of the starting device.Pulling the "suction", the driver, as it were, brings the starting device into a cocked state. Wherein:

  • The three-arm lever is “cocked” with a cable counterclockwise,
  • Carries out telescopic traction
  • The rod, in turn, rotates the air damper through the lever.
  • The second lever arm presses on the axis of the choke 1 of the chamber.
  • The airflow damper is now completely closed, the throttle damper of the chamber 1 is slightly ajar for starting, creating a starting gap

When adjusting the starter with your own hands, you first need to remove the carburetor. Then:

Turn the choke lever so that it closes. Now the device is cocked.

Now you need to turn the carburetor over, measure the gap between the edge of the throttle valve (1 chamber) and its wall. For carburetors "seven" this gap is 0.85-0.9 mm. The gap can be measured with a probe calibrated wire:

To bring it into this range, the drive rod on the throttle valve is bent.

After that, set the gap "A". It is located between the channel wall and the bottom edge of the air damper. To do this, close the shutter again, “cock” the device. To create an imitation of rarefaction of air, we sink the rod of the starting device:

Now the rod pulled the thrust through the slots, and as a result the damper opens. The clearance "A" is 5-5.4 mm.

To adjust this gap, you need to turn the adjustment screw with a screwdriver, only first removing the screw plug from it:

How to set idle speed on a VAZ 2107

First you need to make sure that the ignition system is correctly configured, all wires are working and the engine is fully warmed up.

  • We tighten the “quality” screw of the mixture to maximum revolutions (counterclockwise), while the mixture is enriched with fuel,
  • Rotating the “quantity” counterclockwise, we set an even higher frequency on our own.
  • We carry out a “quality” check: is it possible to add more momentum.

The meaning of this operation is to wrap the “quality” with a constant “quantity” of up to 850-900 rpm.

Speed ​​can be estimated by the electronic tachometer, with skill - by ear, or by the tachometer of the dashboard.

The next step is regulation of the choke drive.

If you do not pay attention to the position of the drive, the machine may stall. To do this, you need a simple slotted screwdriver, and a 7 mm open end wrench.

The figure shows the position of the shutter when the recessed and elongated "suction".

To adjust, do the following:

  • "Suction" is drowned,
  • We remove the thrust fixing screw with a slotted screwdriver (the spring pushes it vertically)
  • Tighten the screw
  • Check the shutter stroke.

Adjust the throttle actuator ("gas").

If this drive is improperly configured, acceleration dynamics and engine responsiveness deteriorate. This setting must be done with an assistant.

You will need an open-end wrench for 8, a screwdriver, a flashlight and a vernier caliper.

Completely "drown" the "suction", or drive the air damper.

  • Now your assistant completely depresses the gas pedal all the way to the floor. This opens the throttle completely, as shown below, for fidelity, you can illuminate the first camera with a flashlight. After releasing the pedal, the shutter should completely close the first chamber without gaps.

To adjust the caliper, we measure the length of the rod, it should be exactly 8 cm. Using the rotation of the tips, we "adjust" the length of the rod to this size by unscrewing the "locking" nuts.

After that, we put the thrust in place and repeat the test. Modern traction is often made from very poor plastic that shrinks. Therefore, in a week or two, you need to check the "running-in" of traction.

You may not know how to adjust the VAZ 2107 carburetor, but everyone can set the length of the thrust.

We considered only a few possibilities to do the carburetor adjustment with our own hands. In general, there is a whole profession "carburetor", which implies full ownership of this necessary and complex technology. In one article, it is simply impossible to describe all the nuances of this process. But we hope that the basic principles were clear and useful for you.

How is the carburetor

If at first glance the carburetor circuit may seem super complicated, then after a more detailed examination everything will become clear. It consists of:

  • throttle
  • nozzles
  • air and fuel channels
  • spray gun
  • diffuser
  • mixing chamber
  • float and float chamber,
  • locking valve.
Carburetor device

Now it is worthwhile to consider in more detail the principle of operation of the unit. The float connecting to the needle valve is responsible for maintaining the optimum amount of fuel in the float chamber. When the engine is running, the fuel level in the chamber decreases, which causes the float to drop. This leads to the opening of the needle valve, so that the required amount of gasoline enters the fuel chamber. As soon as the fuel level in the chamber is sufficient, the float will again block access to the chamber.

On a note! Even if the vehicle is angled, fuel does not spill out of the float chamber. This is due to the fact that the level of the outlet is slightly higher than the fuel level in the chamber itself.

Common problems

Among all the problems that motorists have to face, it is worth highlighting the most common: unstable engine operation, contamination of spark plugs and gasoline leakage. All of them can arise regardless of the nature of driving a vehicle or its year of manufacture. We consider each of these reasons separately.

Detailed information about the causes of detonation and how to eliminate it can be found here. You may also be interested in an article on the sizing of oil scraper rings.

Gas leak

At the first sign of leakage, that is, if fuel leaks are noticeable on the carburetor body, first of all, it is necessary to check the float and the float chamber. It will also not be superfluous to check the fuel pressure level. If the pressure ranges from 4 to 7 atmospheres, then everything is in order and the problem must be sought already in the float chamber. As practice shows, the camera will be easier to replace than playing with it.

Inspect carburetor body for leaks.

Soiled spark plugs

The use of low-quality gasoline, breakdown of oil scraper rings or malfunctioning of the carburetor and other components can lead to contamination of spark plugs. Also, carbon deposits may indicate an excess supply of gasoline. On the carburetor side, an unregulated float or a blown valve may be a causative factor. Check all possible problems and fix them.

Dirty candles are a fairly common problem.

Idle swimming

Unstable engine operation may indicate a problem with the wire coming from the carburetor to the accelerator pedal. To check, it is necessary to disconnect the wire from the carburetor and pull the throttle by hand. Do this with the engine running. If during this procedure the engine speed drops to normal values, then the fault should be sought in the wire. Otherwise, the carburetor itself is to blame. Carefully clean it from corrosion and accumulated dirt.

Unstable engine idling

How is the adjustment

The adjusted fuel supply with air improves engine performance, and the adjusted idle speed does not allow the unit to work in too slow or fast mode. You can adjust the carburetor of your car yourself, especially since for this work special tools or knowledge are not needed. It is enough to prepare paper towels, clamping devices, pliers and a set of screwdrivers. Further, everything is quite simple.

Method number 1. Fuel mixture adjustment

Step 1. Stop the engine - this is the first point in the carburetor adjustment process.

First, turn off the engine

Step 2 Lift the hood and lock it in that position. In most cars, for this you need to pull the lever in the cabin (somewhere near the steering wheel), and then raise the hood itself.

Raise the hood of the car

Step 3 After you find the air filter in the engine compartment, unscrew the fixing nut (wing nut).

Unscrew the wing nut

Step 4 Since the filter is attached to the carburetor body, remove it. This should not cause any problems, since the fastener has already been unscrewed.

Remove the filter element.

Step 5 Find two special bolts on the front of the carburetor. They are designed to adjust the flow of the fuel-air mixture.

Step 6 Start the engine and let it run for 10-15 minutes. This should be enough for it to warm up to operating temperature. By indicators on the dashboard or by the sound of the motor, you can determine when it is warm enough.

Preheat engine to operating temperature

Step 7 Using a screwdriver, gently turn the first adjusting bolt clockwise until the engine starts to malfunction or stall completely.

Slowly turn the first adjusting screw

Step 8 Do the same with the other adjustment bolt. At the same time, it is necessary to ensure that both bolts are adjusted equally - this way you can achieve uniform mixing of fuel and air in the carburetor. After that, slowly turn the bolts in the opposite direction until the smooth operation of the engine is heard. Turn the bolts one at a time, but in no case at the same time.

Now adjust the second bolt

Step 9 Having determined the point while scrolling the adjusting bolts at which the engine works best, install the air filter in its place. Of course, after such a procedure, it is advisable to change the filter element, but if you could not get a new part, then temporarily put the old filter.

Having achieved optimum engine performance, install the filter in its place.

Method number 2. Idle setting

Step 1. Setting should be carried out only on a warm engine, so before that you can ride your car for about 10 minutes. If you are adjusting in the winter, then the time for warming up should be a bit longer. According to the above instructions, remove the air filter.

Warm up the engine before work

Step 2 Find under the hood the throttle and the cable leading to it. There should also be an adjustment screw (see photo).

Find the accelerator cable

Step 3 Start the engine with the air filter removed.

Remove the air filter and start the engine.

Step 4 Gently tighten the idle adjustment screw. You need to turn it clockwise, half a turn will be enough.

Proceed to idle tuning

Step 5 When tightening the adjusting screw, listen carefully to the engine. All sounds should be clear. In order for the engine to adapt to the change, it is necessary to wait 10-20 seconds after turning the bolt.

Watch the sound of the engine when turning the screw

Step 6 Turn the adjusting screw gradually until a smooth engine operation is heard. Each time, the bolt must be turned no more than half a turn. Once the work is completed, install the air filter in place.

Reach the filter for optimum idle performance.

Tips & Tricks

Almost all cars are equipped with a tachometer, with which you can adjust the idle speed (shows the number of revolutions per minute). But first, you need to read the user manual to check the correct speed.

On a note! If the idle setting did not give the desired result, then adjust the fuel supply with air, following the above instructions. When the adjustment screw is tightened, the idle speed indicator rises, and when unscrewed, on the contrary, it drops.

In conclusion

If this is your first time setting up a carburetor in your car, it may not work the first time. To achieve its smooth operation in all respects and at different engine speeds, even an experienced driver can take more than one day. When driving, you need to listen to the car and, if necessary, regularly make adjustments to the carburetor.

DIY carb setting

As soon as you manage to ensure the correct operation of the carb, fuel consumption will decrease significantly, and the fuel system itself will operate reliably and without interruption. All you need is desire and some free time. Not a nail, no wand, dear motorists!