Town Car V8-302 5.0L (1987)
Vacuum Delay Valve: Description and Operation
Vacuum Delay Valves
Types Of Vacuum Delay Valves
This valve, Fig. 23, further reduces emissions by delaying the spark advance during rapid acceleration and by cutting off advance immediately
upon deceleration. This is a one-way valve and will not operate if installed backwards. On all systems which employ the dual diaphragm
distributor, the line which has high vacuum at idle (normal operating temperature) is connected to the secondary (retard) side of the distributor
vacuum advance unit. This is the connection closest to the distributor cap.
