Do-it-yourself tuning and modification of the Solex 21083 carburetor

Solex carburetors series 21083 are installed on cars equipped with contactless ignition systems. The design of the emulsion-type device has two chambers. The throttle valves are opened sequentially.

The carburetor is equipped with the following systems:

dosing of both chambers;
idling of the feather chamber;
transition of both chambers;
semi-automatic start;
diaphragm type accelerator pump;
economizer modes.

The basic model of the 21083 series has the smallest diffuser diameter and is designed for engines up to 1.5 liters. This carburetor is a universal device. It can be modified for any modification of the power plant by turning the diffusers to the required cross-section.

It is not recommended to install a carburetor on engines with a volume of more than 1.5 liters due to the fact that at high speeds it will “choke” the engine. Since 21083 produces a lean mixture, to increase dynamics on UZAM engines, the jets should be replaced.

A little about the carburetor

This type of carburetor is installed on a car that contains non-contact ignition systems. This device has 2 cameras. The throttle valves open in sequential order.

The carburetor contains a number of specific systems:

Design solutions

Features of the internal combustion engine of the base model 2108 are:

the length of the valves and connecting rods has been reduced - making it possible to reduce the dimensions of the internal combustion engine and the noise from its operation;
the oil pump is shifted to the crankshaft end - to reduce the size of the unit;
efficiency
The shape of the combustion chamber is copied from Porsche engines.

When designing the engines, it was planned to carry out a major overhaul after 120 thousand kilometers. In practice, the resource turned out to be twice as high.

The process of setting up a Solex carburetor

To adjust the 21083 carburetor for the UZAM engine, you should start by setting a specific level in the float chamber. Level adjustment must be made relative to the lid. To perform this operation, you need to use a special template suitable for your type of carburetor. Such a template is usually found in a special user manual. Without it, you will not be able to complete this task yourself.

After adjusting the float level, you need to make an adjustment for the idle speed.

To do this, you need to perform a number of sequential operations:

Remove the fully tightened quality screw. It is in the position of approximately 6 turns. When the vacuum in the vacuum hose disappears, you need to stop rotating. This hose is directed to the distributor.
Check the power plant, which is in a warm state. The test is to see if the engine can maintain idle speed from a thousand to 1500 per minute. If the number of revolutions reaches 800 per minute, then this number should be reduced. To achieve this, you need to additionally unscrew the screw.
In order to achieve stable operation of your engine, provided that the mixture is as lean as possible, you need to turn the screw more gradually. It is worth understanding that the more the screw is tightened, the leaner the mixture, and therefore CO2 emissions will be minimal.
For a warm engine, you need to set the idle speed to around 900 per minute. This number is suitable for the summer period of the year. And in winter it will require approximately 1000 rpm.

Depending on the size of your engine, the choice of jet is made. Remember that the larger the engine volume in your car, the less jets are needed.

For the first chamber, a fuel and then an air nozzle are initially selected. After this, jets are selected for another chamber.

Turbine installation

You can improve the driving performance of your car by installing a turbine. VAZ 2109 carburetor tuning is often carried out using this method, since it is highly effective. Installing a turbine leads to a significant increase in the power of the power unit, as the amount of air and fuel in the cylinder increases. An increase in the volume of the combustion mixture causes a significant increase in power. If more energy is released in the cylinder at the time of fuel combustion, the pressure created by the gas increases.

The gas pushes the piston, the higher the pressure on it, the greater the power. However, it should be taken into account that the presence of a turbine in the system, which pumps air mass and fuel, leads to a number of breakdowns with the distribution of air flows when operating in different modes. The important points of turbine installation include:

The turbine increases the air density in the manifold through which the air mixture is introduced. This moment determines a significant leanness of the mixture. The problem can be solved using special fuel jets that have increased performance. Increased productivity occurs due to an increase in the cross-section of the inlet diameter. A jet of this type allows the carburetor to operate stably at low speeds due to the supply of the required amount of air. Also, increasing the speed to medium and high values does not lead to failures.
The charge air pressure differs in different operating modes. In this case, there is a direct proportionality between the rotation speed of the manifold and the air pressure indicator. Oversaturation of the mixture with air often leads to a significant decrease in the flow rate through the diffusers. In some situations, the fuel supply may be cut off, causing the engine to shut down.
The use of a turbine leads to a significant reduction in the degree of compression of the working medium when compared with the atmospheric version. When using the carburetor in question without changing it, the compression ratio is 10-11, then when installing a turbine it drops to 8.7-9.6. This point is determined by the operating rules of the internal combustion engine, since strong compression at high saturation can lead to fuel detonation. The problem under consideration can be solved by increasing the volume of the combustion chamber, for which additional gaskets are used under the head. An increase in volume without changing the piston stroke determines a decrease in the compression ratio.

The above points determine that a turbine can be installed only if the carburetor itself is changed. If the work is done correctly, you can achieve impressive power levels at all speeds. VAZ 2109 carburetor tuning is carried out by increasing the elasticity of the power unit at medium and high speeds, taking into account the need to achieve full filling of the combustion chamber at low speeds.

In addition to the above points, certain disadvantages of doing such work should also be highlighted. These include the following:

1. It is necessary to carry out design changes to the carburetor.

2. It is necessary to change the design of the cylinder block.

3. There is a possibility of problems with valves, cylinders and pistons due to a decrease in the compression ratio.

4. If the pressure is too high, valves and cylinders may burn out, which will lead to a decrease in engine life.

Only after assessing the amount of work and the possibility of the above problems occurring can you begin work on installing a turbine and changing the carburetor along with the cylinder block.

Table of engines and fuel VAZ 2109

Engine and fuel VAZ 2109
engine's type	L4	Engine location	front, transverse
Engine capacity, cubic meters cm	1288	Supply system	carburetor
Power, hp/rpm	64/5600	Fuel type	petrol
Torque, Nm/rpm	95/3400	Consumption, l per 100 km	5.7
Boost:	–	Valves per cylinder:	2

Carburetor improvement

If the efficiency of the Solex 21083 carburetor does not suit you, then you can modify it. For this, several different options have been invented. Let's try to look at some of them.

Adjusting the new level in the float chamber, as well as replacing the valve needle.

This upgrade is done to create more stable carburetor operation. In addition, this will make it possible to stop creating a rather lean mixture at high-power, as well as in transition modes. The needle has a high level of reliability, and it also has high damping characteristics. Thanks to this, the set speed level will be at a more stable level.

Sawing the throttle valve.

To reduce CO2 emissions, you need to reduce the cross-section of the hole in the throttle valve. Thanks to this action, when driving your car, fuel consumption is reduced by two percent. Another advantage is that when idling, the distribution of fuel among the cylinders will be more uniform.

Specifications

Before we begin to describe the process of refining and increasing the power of the VAZ 2109 carburetor engine, it is worth understanding what power units were installed on the vehicle, and also consider the main technical characteristics.

During the production process, the “nine” was equipped with three options for carburetor engines:

21081 (1.1 8V)

Name	Index
Volume	1.1 liter (1099 cc)
Number of cylinders	4
Number of valves	8
Fuel	Petrol
Injection system	Carburetor
Fuel consumption	6,7
Cylinder diameter	76
Cylinder operating order	1-3-4-2

2108 (1.3 8V)

Name	Index
Volume	1.3 liters (1289 cc)
Number of cylinders	4
Number of valves	8
Fuel	Petrol
Injection system	Carburetor
Fuel consumption	7.0 l
Cylinder diameter	76
Cylinder operating order	1-3-4-2

21083 (1.5 8V)

Name	Index
Volume	1.5 liters (1499 cm3)
Number of cylinders	4
Number of valves	8
Fuel	Petrol
Injection system	Carburetor
Fuel consumption	7.0 l
Cylinder diameter	76
Cylinder operating order	1-3-4-2

Do-it-yourself Solex carburetor tuning

There are several methods for modifying this carburetor. Most often, tuning is done by boring and grinding various surfaces, as well as smoothing corners. Before the finalization process, it is worth preparing some tools. Such as screwdrivers of various types, items for grinding, a compressor, as well as a special liquid for washing parts.

After you have removed the carburetor and disassembled it, you need to carry out a number of operations:

Clean carburetor parts.
Use a file to file off the protruding parts of the screws that are located on the throttle valve.
Grind off the damper shaft as much as possible.
The lower part of the carburetor must be thoroughly washed.
The dampers and their axles need to be pulled out.
Use a file to round off the B3 axis. After this, you need to tighten the bolts with a cone-shaped head.
After assembling the entire throttle mechanism, various errors in the initial stamping should be smoothed out.
Accelerator pump tubes need to be installed in 2 chambers.
If the mixing chamber has any irregularities, they need to be smoothed out.

Let's summarize: Such carburetor tuning can increase its performance several times.

Settings

Remove the minus terminal from the battery and the air filter.
Slightly open the bolt that secures the linkage to the choke lever.
Turn the air damper lever until it is completely open.
In the cabin on the instrument panel there is an air damper drive lever - press it all the way.
Pull the rod all the way out and tighten the bolt that secures the rod to the air mixture lever.
Pull the air damper control lever on the instrument panel all the way. If the air damper does not close completely after this, then slightly open the bolt securing the traction cover and, moving the cover, completely close the throttle damper. The bolt can now be tightened.
Place the minus terminal and filter in place.

Content

Carburetors became familiar to everyone with the arrival of VAZ cars on the car market. When creating the VAZ 2109 model, a Solex carburetor was used, which at one time had good performance. The engine could operate correctly under various driving conditions. Considering the features of engine operation, it should be noted that to ensure maximum power, the resistance in the intake tract must be at a minimum level. This moment allows air to penetrate into the combustion chamber in a large volume. When operating at medium and high speeds, in this case, it is possible to achieve high power figures, but the instant opening of the damper reduces the vacuum in the diffuser, and this causes the mixture to become leaner.

Sidebar: Important: Reducing the rate of air filling of the chambers leads to a decrease in power at low speeds. Carburetors, which are installed on VAZ 2109 and 21083 cars, have a main diffuser diameter of 21 mm and 23 mm. This solution makes it possible to enrich the mixture well with air at low speeds, but at the same time the power is reduced at medium and high speeds.

Eliminating air leaks

One of the most common problems is excess air sucking under the carburetor. You can also handle this on your own. To do this, it is necessary to increase the pressing area of the carburetor flange (provided that there is no deformation of the carburetor cover). You will need corner pads (VAZ 2101–2107), in which we drill holes up to 8.2 mm in diameter. Now all that remains is to replace the factory washers with these pads and tighten the nuts.

If the cause of air leaks is a deformed cover, you can replace the factory gasket by making a new one yourself. It can be made from thicker cardboard or other suitable material. Lay a fabric thread along the contour of the gasket and along the contour of the holes and secure it with any gasoline-resistant glue. Grinding the bottom plane of the carburetor cover can also give a good result.