Main dosing system of the Stromberg 175 CDT carburetor
1 - cap; 2 - piston; 3 - spring; 4 - jet; 5 - needle; 10 - throttle valve
The vacuum created by the engine in the intake manifold enters the cap 1, which ensures that the piston 2 rises, the pressure under which is equal to atmospheric. As soon as the force created by the rarefaction and the force of the spring installed inside the cap 3 are balanced, the position of the piston is stabilized, and it gives access to a certain amount of air and ensures the dosage of fuel sucked in by the jet 4 through a conical needle 5 that regulates the flow area of the jet 4. The shape of the needle is specially selected to achieve the best fuel dosage at any position of the piston in the cap.
Idle system
The piston is in a position that provides minimal access to air and fuel.
Idle speed adjustment is carried out by changing the degree of opening of the throttle valve.
The solenoid valve installed at the bottom of the jet cuts off fuel access to the carburetor when the engine is stopped and in case of exceeding the maximum engine speed.
Enrichment of the combustible mixture during acceleration
The oil shock absorber slows down the piston rise under the action of vacuum in the cap. The vacuum in the intake piping acts on the jet. This ensures the supply of additional fuel.
Stromberg 175 CDT carburetor starter
2 - piston; 6 - spool; 7 - starting device; 8 - ball valve; 9 - thermal valve; 10 - throttle valve; 11 - economizer control lever
The enrichment of the combustible mixture when starting a cold engine is carried out by spool 6 with calibrated holes that provide an increase in idle speed (by supplying additional air) and an increase in the amount of incoming fuel.
The movement of the spool is controlled by a starting device with an electric (heating with time delay) and pneumatic drive (due to vacuum in the inlet pipeline), the effect of which is adjusted depending on the temperature of the coolant. Under the action of a spring, the diaphragm of the starting device 7, which is under the action of atmospheric pressure, opens the ball valve 8, which allows access to the fuel-air mixture enriched in the thermostat-controlled spool. After starting the engine, the spool gradually closes, its holes overlap, limiting the flow of the combustible mixture.
After starting the engine, the thermal valve 9 closes the channel of communication with the atmosphere of the starting device. Under the influence of vacuum in the inlet pipeline, the ball valve 8 closes, and the spool 6 rises. The enrichment of the combustible mixture stops.