Ignition Timing: Adjustments

Ignition Timing Marks:

Set timing at slow idle and Before Top Dead Center, unless otherwise specified.

U.S. models except high altitude, leave vacuum hoses connected.
High altitude and Canadian models, disconnect and plug distributor vacuum hose.

ADJUSTMENT CONDITIONS:
Coolant temperature, 185°F-203°F.
All accessories, Off.
Transmission, N (Neutral).
Parking Brake, ON.

1. Connect timing and tachometer.
2. Start engine and run at curb idle speed.
Standard value
Curb idle speed 800 ± 100 rpm

Dual Diaphragm Vacuum Advance:

3. When testing ignition timing at altitudes above 3,900 ft. disconnect the white striped vacuum hose from the sub-vacuum chamber of the distributor and plug the hose end.

4. Check basic ignition timing and adjust if necessary.
Standard value
Base Timing 5° ± 2° BTDC

5. TO adjust ignition timing, loosen distributor mounting nut and turn distributor housing.
6. After adjustment, securely tighten mounting nut.