Nova/Chevy II L4-1600cc 4ALC Nummi (1988)
Distributor Vacuum Control: Testing and Inspection
Vacuum Advance
Distributor Angle Advance Characteristics
Vacuum Advance Inspection
1. The distributor vacuum advance unit is controlled by negative air pressure from the vacuum advance port of the two barrel carburetor.
2. During normal operation, negative air pressure exerted by advance unit "A" of the carburetor is sufficient to regulate the vacuum advance.
3. Disconnect the vacuum hose, then connect a vacuum pump to the diaphragm.
4. Apply vacuum and check that the advancer moves. If the vacuum advancer does not work, repair or replace as necessary.
Governor Advance Inspection
1. Turn the rotor clockwise, release it and check the rotor returns counterclockwise.
2. Check that the rotor is not excessively loose.