Solenoid Vacuum Valve
Attached to ignition coil bracket (V-8 engines) or to a bracket at rear of intake manifold (6 cylinder engines). When valve is energized, carburetor ported vacuum is blocked and distributor vacuum line is vented to atmosphere through a port in the valve, resulting in no vacuum advance. When valve is de-energized, ported vacuum is applied to distributor resulting in normal vacuum advance.