Flo-jet Carburetors or Gravity Feed
First, let us consider the gravity feed system. The tank is above the carburetor and fuels flows by gravity. Notice an air vent hole in the tank cap so that air can flow in as fuel flows out and a air vent hole in the carburetor bowl so that air can
flow out as fuel flows in. If one or both of these holes were plugged, the flow of fuel would cease and stop the engine.
As the fuel enters the bowl, it raises the float. The float in turn raises the needle in the float valve. When the needle touches the seat, it shuts off the fuel flow, and the position at this time is called the float level.
Float Level
The float level in general should be high enough to afford an ample supply of fuel at full throttle and low enough to prevent flooding or leaking.
To set the level on the carburetor, invert the upper body. The float and the body cover should be parallel. If not, bend the tang on the float to obtain this position. The actual distance in the small carburetors is 5/16
of an inch between the float and the gasket. On the larger models it is 3/16 of an inch. The float level is not as critical as on some carburetors.
Remember, however, that there should be one gasket between the float valve seat and the carburetor. Now, the fuel is down into the bowl but how does it get into the cylinder?
The position of the nozzle and the fuel level. The fuel in the bowl seeks its own level, which is well below the discharge holes. Notice that the discharge holes are in the venturi, the place of greatest air velocity.
As the piston in the cylinder moves down with the intake valve open, it creates a low pressure area that extends down into the carburetor throat and venturi. Two things start to happen.
