K151C (carburetor): adjustment, arrangement and operating principle

K151C is a carburetor designed and manufactured at the Pekar plant (the former Leningrad carburetor plant). This model is one of the modifications of the 151 line of carburettors of the manufacturer. These units are designed to work with the engine ZMZ-402 and various modifications of these engines. After some refinements and upgrades, K151C (a new generation carburetor) could work with such engines as ZMZ-24D, ZMZ-2401, UMZ-417 and many other units of similar design.

This device is equipped with the majority of modern systems and mechanisms designed to improve technical and operational as well as environmental characteristics. Consider the design of the device, the principle of operation, methods of repair and adjustment.

Design

K151C - carburetor, which is equipped with two metering devices in the first and second fuel chambers. Also this model is equipped with an idling system, a semi-automatic launch system, an economizer. The design provides an accelerating pump that sprays fuel into the first and second chambers. Along with other systems, there is EPHC with pneumatic drive and electronic control.

What is the peculiarity of a stepless semi-automatic start-up system? Thanks to it, you no longer need to press the accelerator pedal to start the cold motor.

The unit has two vertical channels for air. In the lower part of them is the throttle. These channels are called carburetor chambers. The throttle and its drive are designed in such a way that, as you press the accelerator, one circuit first opens, and then the other. This is a two-chamber carburetor. The outline, whose flap opens first, is called the primary one. Accordingly, the secondary chamber goes further.

In the middle part of the main channels for air passage, special tapers of a cone-shaped shape are installed. These are diffusers. Due to them, a vacuum is formed. It is necessary that in the process of air movement the fuel from the carburettor float chamber is sucked. In order for the device to function properly and prepare the optimal mixture, the level of gasoline in the chamber is constantly maintained. This is done using a float mechanism and a needle valve.

How does the K 151 carburettor work? K151C consists of three main parts. The upper one is the housing cover. It is equipped with a flange and studs, a device for ventilation of the float chamber, as well as details of the starting system.

The middle part is directly the body of the unit. Here there is a float chamber, a float mechanism, fuel supply systems. In the lower part are installed throttle valves and their bodies, the device idling.

Main dosing system

There are two systems. They have the same design. The systems are equipped with fuel jets. Their reader can see in the photo below.

The main jet is installed on the top of the case. To be more precise, in the area of emulsion wells. Under the air nozzles there are 2 emulsion tubes.

In the walls of the emulsion wells, holes are provided that are connected to the outlet nozzles. Due to rarefaction in the area of the nozzles, the fuel rises through the emulsion wells. Then it passes to the holes in the tubes. Then the fuel is mixed with air in the central part of the tubes. After that, it leaves through the side channels to the sprayers. There, the fuel mixes with the main air.

Idling system

It is necessary to ensure stable operation of the engine at idle. The system consists of several elements:

1. The bypass channel.
2. Screws, by means of which adjustment of the carburetor K151C is carried out.
3. Fuel and air jets.
4. The economizer valve.

Accelerating pump

It allows the engine to operate stably on the entire range, without failures when the accelerator pedal is pressed hard.

The pump is an additional channel in the body of the carburetor, a ball valve, a membrane mechanism and a sprayer.

Econostat

This system is necessary to improve the stability of the power unit at high speed by enriching the fuel mixture. These are several additional channels, through which, due to high dilution with fully open flaps, additional fuel is supplied.

Transition system

It is necessary for the engine speed to increase more smoothly when the throttle of the secondary chamber is opened. The transition system is a fuel and air jet.

Optional equipment

This is what K151C is. The carburetor is additionally also equipped with a filter in the form of a protective mesh. The unit also has a reverse fuel channel. Through it, excess gas goes into the gas tank.

Differences K151C from the basic carburetor K151

We examined how the carburetor K151C is arranged.

The device, at first glance, almost does not differ from the entire 151-series. However, there are some minor differences. Thus, the small diffuser has a more refined design. In the carburetor, the accelerator pump is used for two chambers at once. Also, the developers changed the profile of the cams on the pump drive. The air damper drive is now stepless. This makes it much easier to start a cold engine. Also changed the settings of the dosing systems. Thanks to this, it was possible to improve the environmental performance.

K151C - carburetor is more effective than K151. So, with him, the dynamics of the car improved by 7%. Up to 5% fell fuel consumption when driving in the urban cycle. The start of the engine has improved significantly, and the engine has stabilized at idle.

How to connect the carburetor?

Owners of old cars often do not know how to attach this device. Connecting carburetor K151C is as follows.

The design has 2 hoses. The main fuel connection is connected to the fitting located under the float chamber, the one that is closer to the motor. The return fuel channel is connected to the lower branch. It can be seen in the opposite side of the engine, lower than the main fitting.

Also it is necessary to connect two more thin hoses. One of them can be connected to the economizer valve of idling. This is the hose that comes from the solenoid valve. The second is connected to the bottom connection from the back side of the throttle valves.

Also you need to connect the OZ hose to the trampler. The carburetor has a hose connection for forced ventilation of the crankcase. It also needs to be connected.

Carburetor К151С: repair, adjustment

Several types of adjustments are carried out. So, you can adjust the idling speed, fuel level in the float chamber, throttle and air damper position.

The fuel level is changed by the bending of the float. The parameter is measured on a special surface in the float chamber. It is better to entrust this operation to professional masters, but if necessary, you can do it yourself.

To adjust the idle speed, warm up the engine to its operating temperature. Next, open the throttle and unscrew the adjusting bolts:

• Quantity screw with spring;
• Screw quality.

The engine will pick up speed. Then the screws are tightened until the motor becomes unstable. Then the quantity bolt increases the speed until the engine runs smoothly. The adjusting mechanism responsible for quality, twist up to the stop. What do you do after that?

Further, the quantity screw is twisted so that the motor stays stable at 700-800 rpm. If the quantity screw is wrapped more, there will be dips when the gas is pressed. If the speed is high, they are reduced by adjusting the throttle position.

Conclusion

We examined the carburetor model 151C. Repair of the carburetor K151C and its adjustment, as can be seen, can be carried out by hand. This is convenient if the failure happened far from the SRT or home. And even beginners can serve the carburetor.