Distributor Vacuum Vent Valve: Description

Some engines require a Distributor Vacuum Vent Valve. The functions of this valve are to prevent fuel migration to the distributor vacuum advance diaphragm and to act as a spark advance delay valve. The valve helps control exhaust emissions by delaying vacuum advance during light acceleration and by "dumping" vacuum to eliminate vacuum advance during heavy acceleration, deceleration and idle. Although these valves were intended for use in a specific system with an air cleaner mounting, they may be used in other vacuum systems.