Ignition Timing

Set timing at 850 RPM with distributor vacuum line disconnected and plugged. 

Fig 1: Ignition Timing Marks

Courtesy of GENERAL MOTORS COMPANY

• DETONATION NOTE:  If detonation occurs at proper ignition timing setting (caused by low octane fuel or excessive carbon build-up), timing should be retarded 2 1/2°. If extra high octane fuel is used, timing may be advanced beyond specified setting if there is no detonation.