Choke Valve

Choke Valve

Chokes perform the fuel mixture adjustments necessary to start a cold engine. When the fuel-air mixture is too cold, the engine won't start properly, or will stall out periodically. The choke when engaged (closed) the choke causes the fuel air mixture to be increased, or "enriched". The choke is a special valve placed at the mouth of the carburetor so that it partially blocks off the entering air. When the choke plate closes, the vacuum below it increases, drawing more fuel from the fuel bowl. The rich fuel mixture burns even at lower temperatures, allowing the engine to warm up.

The manual choke is a knob on the dash, usually the push-pull type, which extends from the choke on the carburetor to the instrument panel. The driver closes the choke when starting the engine. The main thing to know about a manual choke is to push it back in when the engine has reached normal operating temperature. The trouble with the manual choke is that the driver often forgets to open it fully. This results in a rich fuel mixture which causes carbon to form in the combustion chambers and on the spark plugs. To correct this problem, the automatic choke was developed.

The automatic choke relies on engine heat. The choke valve