Float chamber
The float chamber includes a float, a float shaft, a holder and a needle valve. The movement of the valve is limited by a wire clip. Fuel from the fuel pump passes through the fuel filter and open needle valve into the float chamber. When a certain fuel level is reached, the float rises and by pressing the needle valve stops the flow of fuel. When the fuel level drops, the float drops and releases the needle valve, the valve rises to the stop in the bracket with fuel pressure and opens the fuel to the float chamber. The float chamber is ventilated through an air filter in the carburetor cap. The carburetor has an internal ventilation system.
Starting automation
Starting automatic equipment joins automatically on the cold engine after single pressing a pedal of giving of fuel. The heating unit with a bimetallic plate is controlled from the coolant and from the electric heater. The coolant heater is installed to prevent restarting automatic starting after a short engine shutdown. In addition to starting automation, a TN-starter was installed during the production period of engines of this series (thermally controlled shunt starter). The composition of the working mixture when the engine warms up is regulated bypassing the throttle (shunt device), which accelerates engine warm-up. A stage heater built into the cover of the starter heats the starter automatics depending on the temperature of the engine oil and is controlled by a temperature switch. relay and additional resistance that regulates the voltage.
Idle system
The idle system is located in the 1st stage. Fuel is taken into the idle system behind the main jets. The vacuum that occurs when the throttle is closed, the fuel is sucked from the float chamber into the fuel channel. The air passing through the air jet mixes with the fuel, forming an emulsion that passes down through the open idle valves and outlet holes into the mixing chamber. The composition of the mixture is regulated by the idle speed adjusting screw, the movement of the screw is limited by a protrusion on the plastic cap. To ensure a smooth transition, when the main metering system of the 1st stage is switched on, the air-fuel mixture is additionally supplied through the bypass drillings. To quickly stop the engine after the ignition is turned off, the idle solenoid valve windings are de-energized and the ball valves close the channels under the action of the springs. The idle valves are located so that they block all channels for the passage of the mixture in the idle system.
Main dosing system 1st stage
Fuel from the float chamber through the main jet enters the mixing chamber. With a sufficiently large vacuum, the fuel is sucked through the atomizer into the mixing chamber. With an increase in the speed of rotation, the fuel level in the emulsion channel decreases and the openings of the emulsion tube open. The air passes through the air jets with a modified section into the emulsion tube and, mixing with the fuel, forms an emulsion.
Full load system
The full load system is located in the 1st stage and with the help of two calibrated needles, controlled by vacuum in the intake pipe, changes the flow sections of the air jets. When the throttles are opened, the vacuum acting on the needle control piston decreases. The spring moves the piston up and it lifts the calibrated needles, the ends of the needles of a larger diameter enter the jets. The annular gap between the holes of the jets and the needles decreases, the air flow through the gap decreases, which leads to the enrichment of the fuel emulsion. There is an adjusting screw on the piston, the position of which is set at the factory; additional adjustment of the screw is not required during operation.
Transition system 2nd stage
To ensure smooth activation of the main dosing system of the 2nd stage, a drilling of the adapter system is located directly under the air damper. When the air damper is opened under the action of vacuum, the fuel is sucked into the reserve chamber through the drilling of the transition system. Through the calibrated hole, the fuel from the float chamber flows into the reserve chamber and is sucked in through the pressure pipe. Mixing occurs directly in the gap of the ajar throttle.
Air damper damping 2 stages The damping device is controlled by vacuum and is designed to prevent sudden opening of the air damper. The damper housing is connected by drilling to a vacuum, which counteracts the vacuum in the air damper area. The position of the drilling of the adapter system and the dimensions of the diaphragm are chosen in such a way that the vacuum acting on the air damper tends to open it.
Accelerator pump
Diaphragm type accelerator pump. Fuel injection occurs through a calibrated hole or jet into the carburetor cover.
Fuel is sucked into the pump chamber through the inlet valve from the float chamber. The pump chamber is covered with a layer of heat-insulating plastic. If steam locks occur, they are vented into the float chamber through the ventilation holes. When the diaphragm is pressed, fuel is injected through the delivery valves and a calibrated hole into the mixing chamber. Two discharge valves prevent air from entering the pump chamber when fuel is sucked in.
Check valve
The check valve is controlled by a vacuum in the intake pipe. At idle speeds and partial load modes, the diaphragm moves down under the action of vacuum, overcoming the force of the springs, and opens the valve, the fuel in the return pipe is drained into the fuel tank. In acceleration and full load modes, the vacuum decreases, the diaphragm moves in the opposite direction and the valve closes the drain channel.