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: 8° BTDC
IDLE SPEED: 650 rpm
Fig. 10 Spark advance curves:
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. 10.
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.