Carburetor K-151: device, adjustment, features, circuit and feedback

At the dawn of the production of GAZ and UAZ-31512 passenger cars, carburettors of the K-126 series were installed together with power units. Later these engines began to be equipped with elements of the K-151 series. These carburetors are manufactured by JSC "Pekar". In the process of their operation, both private owners of cars and enterprises faced certain difficulties in repair and maintenance. The fact is that the design of the carburetor K-151 was significantly different from the previous models. At the same time, information about the design features was very scarce.

General information about the 151 series units

Structurally, the elements of the K-151 series are seriously different from all other domestic carburettors, although their nodes and some systems are designed on the basis of typical schemes. Depending on the time of release, the units of this series had several other design options. Below we will consider the features of the carburetor K-151.

General information about the device

The unit has two adjacent vertical channels. They are necessary for the admission of oxygen. At the bottom of each channel is a throttle. Each of them is a carburetor camera. The drive on the throttle is designed in such a way that, as you press the pedal, one flap opens first and only then the other. The chamber, whose shutter is opened earlier, is called primary.

In the middle part of each of the channels for air passage there are special constrictions in the form of a cone. These are diffusers. What are these elements for? Due to them, a rarefaction effect is created, on the basis of which the fuel from the float is sucked into the system. The level of gasoline in the chamber necessary for the carburettor is maintained by means of a special mechanism with a needle valve and a float. We will describe this in more detail.

Float with lower fuel supply

It should be noted that this mechanism is fundamentally different from the same device in any other domestic units on the K-151 carburetors. In this regard, the owners are experiencing problems with maintenance. This is repeatedly confirmed by the reviews. By the way, this element was installed on old engines from ZMZ. Thus, the system, together with a float and a needle valve, is located in the body of the device. Visual control of the mechanism is possible only after removing the cover. At the same time, the natural interaction of the float with the level of fuel will not be violated. This design is called a bottom feed chamber.

Device

So, let's consider in more detail the carburetor K-151. The carburettor arrangement, repair, features are described below. The element is made up of three parts. The upper one is a housing cover equipped with a flange, and also studs for mounting an air filter with a ventilation device of the float chamber and with the elements of the starting system. The last through seven screws is fixed on the case through a paper gasket.

In the carburetor device is the middle part. This is directly the body of the device, where the float mechanism, the chamber and the fuel supply fitting are integrated. Also included is a dosing system. The lower part of the device includes a body for throttle valves together with a drive, an idling device that is attached to the body through a gasket.

The float mechanism

When the fuel chamber is smaller than necessary, the float is lowered, thereby freeing the needle. Due to this, a section is opened and gasoline is supplied. As the chamber fills up, the needle valve closes.

Together with the change in the fuel consumption through the needle valve, the supply of gasoline from the pump also automatically changes. This allows to exclude the increase in fuel pressure at the inlet to the unit.

The level of fuel is never stored - it varies depending on the mode of operation of the engine. So, the maximum level will be at idle. When working at full power, the level decreases slightly. This does not affect the efficiency of the device in any way, since it is necessarily taken into account during the adjustment of the dosing system from the manufacturer.

Dosing systems

That for the first chamber of the carburetor, that for the second, the design of the dosing systems is the same. How is it arranged? Here there are main fuel jets that are installed in the bottom of the float chamber, and the main air jets. The latter are on the plane, at the top of the emulsion wells. Under the main air jets, emulsion tubes are also located. In the middle part of the emulsion wells there is a hole with a large cross section. The latter is connected by special channels to the outlets on the sprayers. They are located in small diffusers.

How do dosing systems work?

On the carburetor K-151, this works as follows. Due to rarefaction in the area of the spray holes, the fuel through the main fuel jet rises along the emulsion well and gets to the holes in the emulsion tubes. Then, gasoline is picked up by air passing through the central tubes. So a fuel mixture is formed, which leaves through the side channels to the sprayers. Then all this will be mixed with the main airflow.

Additional devices in the carburetor

In addition to these basic elements, the carburetor also includes other mechanisms. Thus, the idling system is designed to maintain stable engine operation at speeds up to 1,000 per minute. It consists of a bypass channel, adjusting screws, a fuel and air jet, an economizer valve.

Accelerating pump allows the car to move without failures and, if necessary, accelerate sharply. The system consists of valves in the main body, from a ball valve, as well as from a membrane mechanism and a sprayer. According to the principle of action, it resembles the work of a gasoline pump.

Econostat - a device that allows you to enrich the fuel-air mixture at high engine speeds. Structurally, the element is an additional channel through which, through rarefaction during open throttle valves, the fuel enters the collector. Also in the design there are transitional systems. They are necessary for smooth growth of turns at a time when the throttle valve of the second chamber has just started to open. It is an air and fuel jet.

Malfunctions of the carburetor

During operation, various malfunctions can be observed. So, a frequent problem is high fuel consumption, black smoke from the exhaust pipe with sudden pressure on the gas pedal, unstable idling, bad dynamic characteristics, jerks and dips. In this case, the carburetor K-151 needs adjustment and repair.

Most often among the causes of breakdowns can be identified low-quality fuel. Because of this clogged jets, as well as air and fuel channels. In addition, due to high temperatures, the housing can be deformed. During operation, the jets are exposed to natural wear. Most masters, for whom the device and operation of the carburetor K-151 are familiar to the smallest detail, in the process of repair they try to change the jets at once. It is believed that it is because of them that fuel consumption is increasing, and the power unit can be unstable. But here there is one nuance. Jets, if worn, it is rare enough.

Adjustment

For those who are already familiar with the device of similar units, it will be easy to service the K-151 carburetor. Its elements, disassembly and tuning in general are not much different from all other carburetors. To independently adjust the unit, it is enough to understand the principle and follow the instructions. There are several settings for this device.

Thus, the idle, the air damper, the level of fuel in the float chamber and the position of the throttle can be adjusted. Change the fuel level is only experienced craftsmen, but any car owner can adjust the idling.

Step-by-step adjustment of the carburetor K-151 includes several stages. So, you need to warm up the motor to operating temperatures, then let it run at idle with an open air damper. Next, twist the screws of quality and quantity and allow the engine to gain maximum revolutions. Then each screw is gradually tightened until there are no interruptions in the engine operation.

Using the quantity screw, increase the speed. It is necessary to catch the position when the engine's operation is stabilized. It is desirable that this screw is twisted as much as possible. Do not forget that this bolt also affects fuel consumption. Then rotate the quantity screw. This achieves stable engine performance at speeds of 700-800 rpm. If the quantity screw is twisted excessively, then dips will begin when the gas is suddenly pressed. It must be unscrewed back.

Conclusion

So, we found out what the K-151 carburetor is. Now it can be found only on the old Soviet cars and "Gazelles" of the 90s with a motor from the "Volga" ZMZ-402. Feedback from those who used it, speak of the unreliability of the unit. The most successful are Solex and Weber. Owners say that the K-151 requires constant adjustment and adjustment. In modern conditions it is not suitable for operation.