RENAULT R12 Engine Modification: Operation: Deceleration

When throttle is released and the butterfly throttle valve closes, the vacuum becomes strong enough to move the diaphragm on the decelerator and open the decelerator valve. This allows decelerator to be supplied with fuel and air through metered orifices. The resulting mixture is drawn into the carburetor below the throttle valve. This additional mixture causes a higher engine speed than would normally be the case. This is the "Fast Idling Position".

Fig 1: Decelerator

Courtesy of AMERICAN MOTORS/RENAULT CORP.

Fig 2: Centrifugal Switch (Manual Transmission)

Courtesy of AMERICAN MOTORS/RENAULT CORP.