Distributor Advance Unit: Testing and Inspection

1. Warm up the engine fully.
2. Make sure that the idling speed and ignition timing are within specifications.


IGNITION TIMING: 12° BTDC

IDLE SPEED: 850 rpm

Fig. 19 Centrifugal spark advance curve:

3. Remove the vacuum hose from the distributor vacuum control unit and plug the hose.
4. While gradually increasing engine rpm, check changes in ignition timing with a timing light Fig. 19.

Excessive advance: Governor spring is fatigued (If the governor spring is broken, the initial advance is very quick and high).

Insufficient advance: Governor weight or cam is not operating properly.