Fuel enters between the needle valve seat and needle valve to fill the fuel bowl. The fuel flow is float-controlled. Accordingly, the fuel lever raises the float arm against the needle valve to the point where it seals against the valve seat and shuts off the fuel. As fuel is used by the engine, the level drops slightly an additional fuel is admitted through the needle valve and valve seat. In actual operation, a fairly steady float position and fuel flow condition exists. The fuel bowl is vented to the inside of the air horn through a tube which is calibrated to provide the correct amount of air pressure above the fuel under all operating conditions (Venting provisions are aimed at rapid vapor dissipation to maintain desirable performance under engine idle speed operating conditions and starting a hot engine.)
The fuel bowl vapor vents in this carburetor are located within the air horn. This venting is designed to provide rapid vapor dissipation for best performance under idle and hot start conditions
