Distributor Advance Unit: Testing and Inspection

Fig. 70 Centrifugal advance chart.:

1. Warm engine to operating temperature.
2. Ensure idle RPM and ignition timing are within specifications.
3. Disconnect vacuum hose(s) to vacuum control and plug end of hose(s).
4. While gradually increasing engine RPM, use timing light to check advance Fig. 70. Excessive advance indicates a weak or broken governor spring. Insufficient advance indicates a governor weight or cam malfunction.