Many of us are faced with the problem of choosing the right carburetor for our engine. But not everyone knows how to correctly and from what considerations it is necessary to choose the optimal diameter of the carburetor throttle, and sometimes they make the wrong choice, and as a result they do not get the expected result.
Deciding to install carburettors on my engine, Dellorto ran into a similar problem. Having rummaged through the Internet, I found some information.
In wedge-needle carburetors, the throttle size is the bore under the throttle when fully open. This size is also cast or embossed on the carburetor body along with the abbreviation indicating the type of carburetor. For example PHBE 36BS denotes a Venturi type carburetor with a choke diameter of 36mm.
Initial choice of carburetor with optimal size The choke can be done using the following graph, where the size of the possible choke diameter of the carburetor is shown as a function of the engine power per cylinder.
For example, for a 60 hp two-cylinder engine. For one cylinder we have 60/2 = 30 hp. Thus suitable size carburetor throttle ranges from 32 to 38 mm.
For the Ural motor 750cc with a power of 45 hp. Similarly, we get 22.5 hp. per cylinder, and the optimal throttle diameter is from 28.5 to 34 mm. (I personally chose carburetors with a 30mm choke diameter for my motor)
A carburetor with a large throttle diameter allows for more power at high rpm and, accordingly, higher maximum speed... However, a simple installation of a carburetor with a large throttle diameter on a conventional engine will not increase engine power, since the latter is the result of other additional improvements and modifications to the engine aimed at improving its performance.
A carburetor with a smaller throttle diameter improves acceleration and recoil by low revs... Therefore, when choosing the size of the carburetor, it is worth looking for a reasonable compromise between acceleration and maximum speed.
As a rule, when installing the carburetor bigger size it is recommended to increase the section of the main jet by 10% in comparison with the standard one for every 1mm increase in the section of the throttle. This recommendation assumes that the remaining parts are a needle, atomizer or jet idle move- remain the same.
Before increasing the size of the carburetor on a modified engine, it makes sense to try to install on it a carburetor already fully tuned for an engine with similar characteristics in order to have a good basis for comparison and further modernization, and make all settings on an engine warmed up to operating temperature, having the opportunity check engine operation in different modes and at different speeds.
These small details affect the performance of the machine's engine. If you increase the fuel jet, you can make the car playful, but it requires a lot of fuel. By installing an air jet with a large section, we get a machine that does not develop high speeds, but does not require frequent refueling. It all depends on the wishes of the car owner.
Cleaning, tuning, replacing and adjusting the jets and adjusting the enrichment of the fuel-air mixture is carried out during maintenance and in the event of emergency situations.
The main types of jets and their selection
The industry produces 2 types of carburetor jets, which are included in each repair kit:
- fuel;
- air.
They are made for each camera in the device. The choice of jet depends on the cross-section of the large and small carburetor diffusers. There are different repair kits for each model and car brand. Parts differ in hole diameter. How to adjust the correct operation of the motor is the information every vehicle owner needs.
Quite often, the Solex carburetor is installed on cars of other brands, with the most powerful engines. In this case, the machine will work intermittently, because the VAZ jets will not be able to do their job efficiently - because of the diameter insufficient to supply the enriched mixture.
Often, motorists install a large fuel part for better acceleration and dynamic driving. In this case, one should not forget about the increase in fuel consumption. Also, an increased diameter of the nozzle by several orders of magnitude cannot always give good result... How to choose jets, the table will be able to tell.
If the engine capacity is 1.6 liters, you should not put the main jet from a powerful engine on it. If you are no longer satisfied with car acceleration, you may need to look for another reason, for example:
- low compression level in one of the cylinders;
- the ignition system adjustment is out of order;
- one or more spark plugs are faulty;
- replacement of high-voltage wires is required.
These are just some of the causes and malfunctions, eliminating which, you will again get a high-spirited car. The opinions of motorists about redesigning the jets are different, but most believe that it is not worth doing this. Sometimes, those who like to save money install jets that are smaller than the recommended sizes. In this case, it turns out economical, but very weak car, which will take a very long time to accelerate. Ozone carburetor jets should not be installed in a Ford carburetor. They should be on the classic Zhiguli.
Correct adjustment of the carburetor operation can have a great influence on the acceleration and power of vehicles.
Carrying out carburetor adjustment
Each of the carburetors is adjustable in several values. After performing this operation, change:
- filling the float chamber with gasoline;
- the value of the maximum idle speed;
- saturation of the fuel-air mixture entering the engine.
It is quite easy to adjust the quality of the mixture. Every motorist can do this:
- On a warm engine, using the mixture quality adjustment screw, set the number of revolutions, no more than 900 on the tachometer;
- We reduce to the maximum possible - the quality of the mixture, tightening the adjustment screw. We bring the engine to very low speed;
- Gradually unscrewing the screw, we bring the speed to the normal amount so that the engine runs smoothly. It is impossible to overdo it here, it is better to carry out the operation again. Increased idle speed will increase fuel consumption, so additional adjustments are made.
There are situations when the speed has to be increased due to failures in the operation of the motor. For example, if the rotation of the screw does not change the speed. There are several reasons for this breakdown. You need to pay attention to:
- solenoid valve jet - it may be clogged;
- the channel under the screw for adjusting the quality of the mixture. With low-quality gasoline, it clogs up;
- solenoid valve - it is possible that it is faulty.
It is quite easy to check if the valve is working properly. With the engine off, disconnect the wire from the electromagnet, unscrew the solenoid valve and disconnect the fuel jet. Now we turn the key in the ignition lock and bring the wire removed from the valve.
Clicking and sinking the valve stem into the body indicates the serviceability of the electromagnet. Otherwise, we change this device node. Craftsmen advise an easier way. With the engine running, pull off the wire. If the engine has stalled, you can continue to work - the valve is working properly.
If a speck gets into the jet, it should be cleaned. Cleaning is very simple. The jet can be purged using a pump or compressor. Often, the specks are so small that they are not visible, but it is better to play it safe and, if a part is being removed, then it is blown through to eliminate this problem. After completing all the operations, we put the jet in place and check the operation of the system.
It is not always possible to clean the idle channel under the mixture adjustment screw, on the road. Often, it clogs up so much that it cannot be blown out, and the carburetor must be disassembled to eliminate the malfunction. Only then does it become possible to clear this channel. In such a situation, there is a temporary way out.
Use a wrench to loosen the fastening of the solenoid valve on the carburetor until the engine is running normally and drive home. In this case, gasoline passes by the idle fuel jet and this leads to increased fuel consumption. The main "symptom" of this malfunction is interruptions at minimum revs and engine shutdown when depressing the gas pedal, so the obligatory cleaning of the channels and subsequent adjustment will help get rid of the breakdown.
Remember - tuning and adjustment is carried out only on a warm engine, but before that it is often necessary to replace the jet by installing a part from the kit. How to do this correctly, we will consider further.
Replacing the jet
The selection of carburetor jets is carried out according to the marking. Each part number in the kit must match the diameter as shown in the table. When choosing a set of carburetor parts, decide what power, takeoff speed will suit you. If you set the nominal dimensions, then everything is simple - you must first select a kit. This is the most demanding job when buying. It should be remembered that 80% of the parts on the market are from China. Pay attention to this when picking them up. Then you can make repairs.
Important. Engines for VAZ cars are produced with DAAZ carburetors. In almost all modifications, the primary chamber is equipped with a 4.5 atomizer. The main fuel nozzle is marked 135, the air nozzle is number 170. When installing the nozzle number 4, 130 fuel and 150 air nozzles are installed in the first chamber. It is imperative to maintain this ratio.
To carry it out, we need to remove the carburetor from the engine. This will make further work more convenient. The scheme for dismantling the carburetor is described in other articles on the site, the only thing you need to pay attention to is the gasket between the carburetor and the engine body.
Removing the carburetor with a screwdriver, unscrew the cover fixing screws. We remove it and use a flat screwdriver to unscrew the fuel and air jets. On air, it is necessary to disconnect the emulsion tubes. Then, new parts are installed or old serviceable jets are cleaned. For greater confidence, it is necessary to calibrate the jets on a special stand. The "incorrect" parts should be removed, but not done by yourself.
Before installation, all carburetor parts must be rinsed in a cleaning liquid, remove dirt, carbon deposits, and clean all channels. We are starting to install new jets. In this case, the correct location of each part of the mechanism should be observed. The jets on the carburetor must be marked according to the marking.
After assembling the device, install it on a new gasket and tighten the fastening nuts. Primary adjustment and tuning is carried out by the mixture saturation screw and idle speed adjustment. These operations will start the engine. We connect all the hoses and wires, install a new one air filter... We make sure that all parts are in place and securely fastened. We carry out a test run of the engine. Now we need to adjust the operation of the motor and warm it up.
Having looked at the data on the engine temperature, we set up its operation.
After completing all the operations for installing the jets, adjusting the carburetor reliably and following all the instructions, consider how much fuel you will save.
If you have any questions - leave them in the comments below the article. We or our visitors will be happy to answer them.
The selection and refinement of jets on Solex carburetors is carried out in two cases: if it is necessary to increase the power indicators of the car engine (quick start, throttle response, increase in speed) or to reduce engine fuel consumption from the passport indicators.
In the case of an increase in power, the throughput of the GDS fuel nozzles is usually selected and increased (enrich the fuel mixture). Improve if necessary fuel efficiency- increase the throughput of the GDS air jets (deplete the fuel mixture). In any case, it is necessary to install on the carburetor jets with a modified orifice section and a throughput different from the nominal (the marking on the nozzles means the diameter of the hole and corresponds to their certain throughput).
Before starting work, make sure that both the carburetor and the engine are working normally on standard jets. It is also recommended to bring the power supply system and the ignition system of the car into proper condition before carrying out the modification of the carburetor. If the car engine eats up gas in buckets or even doubles, it makes sense to carry out a complete diagnosis of the engine systems, bring everything back to normal, and only then take on the revision.
It should be remembered that when working with the carburetor, it is necessary to adhere to a certain pattern: an engine of a certain volume corresponds to a carburetor with a certain section of diffusers, fuel and air jets of the main dosing systems. A change in one or more of the components of this chain leads to a clear change in the operation of the engine. The increase or decrease in the throughput of the nozzles should be small and gradual - within hundredths of a millimeter. Therefore, for revision, it is better to purchase an additional set of GDS fuel and air jets and perform all manipulations on them. We put the native jets back in case of failure of the experiment.
Options for the refinement and selection of jets on Solex carburetors
- Install air or fuel jets from a different carburetor, from a different engine
You can choose from the lists below.
Table of sizes and applicability of GDS fuel jets for Solex carburetors
| Carburetor models | 1st camera | 2nd camera |
| 2108-1107010 | 97,5 | 97,5 |
| 21081-1107010 | 95 | 97,5 |
| 21083-1107010 | 95 | 97,5 |
| 21073-1107010 | 107,5 | 117,5 |
| 21051-1107010 | 105 | 110 |
| 21083-1107010-31 | 95 | 100 |
| 21083-1107010-35 | 95 | 100 |
| 21083-1107010-62 | 80 | 100 |
| 21412 | 95 | 95 |
Table of sizes and applicability of GDS air jets for Solex carburetors
| Carburetor models | 1st camera | 2nd camera |
| 2108-1107010 | 165 | 125 |
| 21081-1107010 | 165 | 135 |
| 21083-1107010 | 155 | 125 |
| 21073-1107010 | 150 | 135 |
| 21051-1107010 | 150 | 135 |
| 21083-1107010-31 | 155 | 125 |
| 21083-1107010-35 | 150 | 125 |
| 21083-1107010-62 | 165 | 125 |
| 21412 | 160 | 100 |
air jets, fuel jets, emulsion tubes and Solex carburetor wells
- Modify existing jets
On sale there are thin drills 1 mm, 1.5 mm, 1.75 mm, 2 mm, etc. They can be used to drill nominal nozzles to the required size by increasing their throughput. In some cases it is possible to solder the orifice hole with tin and re-drill it.
Jets selection technology
We start the selection from the GDS fuel or air jets of the first carburetor chamber. We install a jet of a reduced or increased cross-section (as a rule, only one hundred square meters) instead of the standard one and check dynamic characteristics vehicle or its fuel efficiency. If necessary, adjust the idle speed with the "quality" and "quantity" screws.
We install an even larger jet, check the dynamics or efficiency. And so several times, until there are obvious failures in the engine operation in different modes. The work is painstaking, requiring time and nerves. Then we take a step back, setting the jet of the present dimension. We carry out a similar setting for the second carburetor chamber (in most cases, they are limited to the first).
This process (in combination with other modifications of the carburetor) is described in detail in the articles on the website,.
The check of the throughput of the jets to control the conformity of their marking can be checked by making homemade device(Cm. ).
Notes and additions
- The selection of jets described above is a minimal interference with the operation of the carburetor with minimal consequences (an increase in power by 5-10 percent or economy within a liter per hundred). You can tune your carburetor more strongly and effectively if you add to the selection of jets, both small and large, select emulsion tubes, modify the mixing chambers of the carburetor, accelerator pump and change the opening sequence throttle valves... A set of measures will allow to fully disclose the hidden reserves of the engine, which will ultimately change and improve the necessary characteristics of the car for the requirements of each particular car owner.
As a rule, they select the types of jets for the Solex 21073 carburetor during its adjustment on the engine. Some of the drivers sometimes think that if a dream has come true and Solex is finally installed on the car, then all problems will be solved at once. But it was not there! The main work only begins after installation. Designed to save you money on fuel resources, Solex needs to be fine-tuned for it to function properly.
It's good if there is a familiar carburetor. And if not? You can try to do it yourself, but for this procedure you need to know at least more information about the carburetor itself.
Selection of types of jets for the Solex 21073 carburetor is one of component parts its settings for the most reasonable further operation. And before changing one to the other, you need to fundamentally understand: why, and what kind of detail is this?
Theory
(banner_content) The engine sucks air through the diffuser, and a certain amount of gasoline through the fuel jet. The volume of the sucked in air and fuel also depends on the volume of the engine. Therefore, there is a tendency: to put a small jet under a larger volume of the engine. And if you have to install a similar Solex 21073 carburetor on a small-volume engine (for example, 1.5), then the standard jets are poor (that is, they give an unsaturated mixture).
Therefore, we can say that everything starts with the fuel jet - its selection and settings. After that, already in the second head, you need to pick up an air one to it. To start - strictly from the first camera, until you set it up, it is not recommended to engage in the second in any case.
Rule: we select the jets according to the volume of the engine. And it is best, before starting the setup, to find the factory Solex, corresponding to the volume of the unit on your car, and rearrange (or put the same) jets from it.
Selection basics
If we put, for example, Solex 21041 (volume 1.8) on the engine 1.5. This carburetor with a diffuser 24x26, fuel - 102.5, which is not enough for a 1.5 engine. We are looking for the coincidence of cameras and a diffuser. We find the closest of the options: Solex 21073. It has a 24x24 diffuser and a TJ - 107.5. And the first cameras are practically the same. By the way, if the diffusers are almost the same, and the volume of the engine is smaller, then the suction of gasoline will be less (the jet is poor). This means that TJ (fuel jets) from 110 are needed. We collect a few.Next, you need to decide what you want to get: economical leisurely or costly throttle response. Depending on the decision, we also select TZ: to adjust the enrichment or depletion of the air and fuel mixture (depleted will lead to gasoline savings, but will affect the acceleration dynamics of the car).
A few examples of how to pick up
1.8 liter engine... Carb - Solex 21073 (24x24). The first chamber is fuel - 115, air - 165. In the second: TZ - 115, air (VZh) - 125th. idle: 41st. In this situation, the consumption of AI 92 for the urban driving mode is from 8 to 9 liters.
Engine 1.5 D... carb - Solex 21073. In the first - TZ 115th, VZh - 155 ZD. In the second - ТЖ 115, ВЖ 135 ZC. XX - 41st. Gasoline AI 80. Consumption - highway 10, city 12.
Additional Information
In general, in addition to the selection of jets, there are also a lot of useful and interesting nuances of setting up Solex, so that it works correctly and is combined with the engine of your carburetor car.
You should always start with setting the levels in the chambers. They are manually set according to the positions of the floats themselves, depending on the unit cover (everything is done according to special templates). And in vain do you think, like many gullible Solex users, that everything has already been exhibited from the factory, they say. In order not to lead to overflows and load on the needle, we make the appropriate settings by bending the tongues of the floats.
After setting the levels, you can do the idle. It depends on the position of the screws, the quality and the amount of the mixture (twist with the suction removed).
Outcomes
It goes without saying that there is no limit to improvement. Sometimes they can even turn into excesses: drill, for example, the throttle valve, polish the MD, solder the epulsion tubes on the carburetor. But, as they say, beyond measure, it is unhealthy. But such a procedure, in its own way fascinating, as the selection of types of jets for the Solex 21073 carburetor, for example, is a thing that is quite necessary for the correct adjustment of the unit and its complete compatibility with the engine compartment. As a result, you get an economical car that responds well to gas.
The selection and refinement of jets on Solex carburetors is carried out in two cases: if it is necessary to increase the power indicators of the car engine (quick start, throttle response, increase in speed) or to reduce engine fuel consumption from the passport indicators.
In the case of an increase in power, the throughput of the GDS fuel nozzles is usually selected and increased (enrich the fuel mixture). If necessary, improve fuel efficiency - increase the throughput of the GDS air jets (deplete the fuel mixture). In any case, it is necessary to install on the carburetor jets with a modified orifice section and a throughput different from the nominal (the marking on the nozzles means the diameter of the hole and corresponds to their certain throughput).
Before starting work, make sure that both the carburetor and the engine are working normally on standard jets. It is also recommended to bring the power supply system and the ignition system of the car into proper condition before carrying out the modification of the carburetor. If the car engine eats up gas in buckets or even doubles, it makes sense to carry out a complete diagnosis of the engine systems, bring everything back to normal, and only then take on the revision.
It should be remembered that when working with the carburetor, it is necessary to adhere to a certain pattern: an engine of a certain volume corresponds to a carburetor with a certain section of diffusers, fuel and air jets of the main dosing systems. A change in one or more of the components of this chain leads to a clear change in the operation of the engine. The increase or decrease in the throughput of the nozzles should be small and gradual - within hundredths of a millimeter. Therefore, for revision, it is better to purchase an additional set of GDS fuel and air jets and perform all manipulations on them. We put the native jets back in case of failure of the experiment.
Options for the refinement and selection of jets on Solex carburetors
- Install air or fuel jets from a different carburetor, from a different engine
You can choose from the lists below.
Table of sizes and applicability of GDS fuel jets for Solex carburetors
| Carburetor models | 1st camera | 2nd camera |
| 2108-1107010 | 97,5 | 97,5 |
| 21081-1107010 | 95 | 97,5 |
| 21083-1107010 | 95 | 97,5 |
| 21073-1107010 | 107,5 | 117,5 |
| 21051-1107010 | 105 | 110 |
| 21083-1107010-31 | 95 | 100 |
| 21083-1107010-35 | 95 | 100 |
| 21083-1107010-62 | 80 | 100 |
| 21412 | 95 | 95 |
Table of sizes and applicability of GDS air jets for Solex carburetors
| Carburetor models | 1st camera | 2nd camera |
| 2108-1107010 | 165 | 125 |
| 21081-1107010 | 165 | 135 |
| 21083-1107010 | 155 | 125 |
| 21073-1107010 | 150 | 135 |
| 21051-1107010 | 150 | 135 |
| 21083-1107010-31 | 155 | 125 |
| 21083-1107010-35 | 150 | 125 |
| 21083-1107010-62 | 165 | 125 |
| 21412 | 160 | 100 |
air jets, fuel jets, emulsion tubes and Solex carburetor wells
- Modify existing jets
On sale there are thin drills 1 mm, 1.5 mm, 1.75 mm, 2 mm, etc. They can be used to drill nominal nozzles to the required size by increasing their throughput. In some cases it is possible to solder the orifice hole with tin and re-drill it.
Jets selection technology
We start the selection from the GDS fuel or air jets of the first carburetor chamber. We install a jet of a reduced or increased cross-section (as a rule, only one hundred square meters) instead of the standard one and check the dynamic characteristics of the car or its fuel efficiency. If necessary, adjust the idle speed with the "quality" and "quantity" screws.
We install an even larger jet, check the dynamics or efficiency. And so several times, until there are obvious failures in the engine operation in different modes. The work is painstaking, requiring time and nerves. Then we take a step back, setting the jet of the present dimension. We carry out a similar setting for the second carburetor chamber (in most cases, they are limited to the first).
This process (in combination with other modifications of the carburetor) is described in detail in the articles on the website,.
Checking the throughput of the nozzles to control the conformity of their marking can be checked by making a homemade device (See).
Notes and additions
- The selection of jets described above is a minimal intervention in the operation of the carburetor with minimal consequences (an increase in power by 5-10 percent or economy within a liter per hundred). You can tune your carburetor more strongly and effectively if you add to the selection of jets, both small and large, pick up emulsion tubes, modify the mixing chambers of the carburetor, the accelerator pump and change the sequence of opening the throttle valves. A set of measures will allow to fully disclose the hidden reserves of the engine, which will ultimately change and improve the necessary characteristics of the car for the requirements of each particular car owner.
