RENAULT R12 Engine Modification: Operation: Acceleration

When vehicle speed reaches 20 MPH (manual transmission) or 20.5 MPH (automatic transmission), contact points on the centrifugal switch (manual transmission) or the computer (automatic transmission) close. Current is directed to the solenoid flap valve and its valve opens a direct line between the decelerator diaphragm and the carburetor body. The vacuum is not strong enough to move the diaphragm as it is held by spring pressure.