Federal CARBURETED 2WD, CALIF. CARBURETED & Fuel Injected Non-Turbo Models
These vehicles are equipped with a dual-diaphragm advance unit. The Sub Advance Control (SAC) is used for additional ignition advance control. Intake manifold pressure is applied to the sub-advancer side of distributor vacuum control unit during idle, low-load operation and deceleration in order to provide an advance angle (Idle Advance System).
Vacuum pressure produced in the advance port is applied to the main advancer side in relation to opening angle of the throttle valve. This provides additional advance angle. The SAC solenoid valve is placed in the intake manifold vacuum line and operates during idle or low-load operation. See Fig 1 .