Carbureted Engine

Fig. 45 Throttle control system.:

This system, Fig.45, is to improve combustion by admitting additional air during periods of gear shifting and deceleration, a throttle opener diaphragm holds the throttle open slightly. The throttle control is made up of two systems, the Dashpot and the Throttle Opener Systems.


DASHPOT SYSTEM

The dashpot system slows the closing of the throttle. When the engine is running, ported vacuum in the carburetor is applied to the throttle opener through the dashpot check valve. On deceleration, the vacuum bleeds off through the fixed orifice in the dashpot check valve, gradually decreasing the vacuum until the throttle closes completely. The speed at which the throttle closes is determined by the size of the fixed orifice in the dashpot check valve, the tension in the throttle return spring and the amount of vacuum generated at the carburetor port.

THROTTLE OPENER

This system facilitates engine starting. When engine is cranked, the cranking solenoid valve is activated through the starter relay to allow intake manifold vacuum into diaphragm so that the appropriate throttle opening angle is obtained.