The quantity of air admitted to the carburetor is controlled by an air valve shown in the air intake by the dotted lines. This is adjusted by hand for a particular engine and is seldom touched afterward.
When starting the engine it is necessary to have a very rich mixture for the first few revolutions, this mixture being obtained by “flooding” the carburetor.
On the Schebler carburetor the mixing chamber is flooded by depressing the “tickler” or flushing pin V.
(107) Two Cycle Carburetors.
Nearly any type of carburetor can be used on a two port, two stroke, cycle engine providing a check valve is placed between the crank case and carburetor to prevent the crank-case compression from forcing its contents back through the inlet passages. A great many manufacturers make special carburetors for two stroke motors that have the check valve built into the carburetor itself. With three port two stroke cycle engines a check valve is not necessary as the piston in this type of engine performs this duty.
In that class of vaporizers known as mixing valves, the valve that controls the flow of gasoline blocks the air passage in such a way that an additional check valve is not necessary.
(108) Kingston Carburetors.
The Kingston Carburetor shown by Fig. 117 differs from the Schebler in many details, the principal difference being in the construction of the spray nozzle and the construction of the auxiliary air valve. The throttle valve E controls the exit of the mixture through the engine connection C which is an extension of the mixing chamber. The spray nozzle J which is surrounded by a hood or tube is controlled by the needle valve A which is threaded into the top of the mixing chamber, this latter adjustment being locked into place by a button head screw and a slot in the casting.
Fig. 117. Cross-Section Through Kingston Carburetor Showing Balls Used for Auxiliary Air Valves.