Vacuum Solenoid Valve (VSV)
This valve is an electrically actuated solenoid and is used on Federal 4 cylinder models equipped with air conditioning and automatic transmission to switch advance vacuum signal from manifold vacuum (A/C off) to ported vacuum (A/C on).
When the A/C is on, the solenoid is energized connecting ports "1" and "2" allowing ported vacuum to supply advance signal to distributor. With A/C off, solenoid de-energizes and ports "2" and "3" are connected to supply manifold vacuum advance signal to distributor.