Vacuum Regulator

3-Port Vacuum Regulator:

Vacuum Regulator (3 & 4 Port):

Three port, Fig. 25, regulators and four port, Fig. 26, 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.

Two port regulators provide a constant output signal when input signal is greater than a preset level. When there is lower input vacuum, the output equals input.