F 250 4WD Pickup L6-300 4.9L (1982)
Distributor Vacuum Control: Description and Operation
3-Port Vacuum Regulator
Vacuum Regulator (3 & 4 Port)
Three port, Fig. 27, regulators and four port, Fig. 28, regulators are used to control the vacuum advance to the distributor. During engine idle
conditions, the manifold vacuum signal is reduced to a constant output signal. Off idle, the output signal equals the spark port.
