Dashpot System

This system slows closing of throttle. During periods of deceleration, ported vacuum in carburetor acts on the throttle control valve through dashpot check valve to hold throttle open slightly. Fixed orifice in dashpot check valve gradually decreases vacuum until the throttle closes completely.

Speed at which throttle closes is determined by size of fixed orifice in dashpot check valve, throttle return spring tension, and amount of vacuum generated at carburetor port above preset level in dashpot check valve.