Ignition Timing: Adjustments

IGNITION TIMING PROCEDURE
- Connect a suitable Power Timing Light to number one cylinder. Or use a suitable magnetic timing unit (use a 10° offset when required).

CAUTION: Do not puncture cables, boots or nipples with test probes. Always use proper adapters. Puncturing the spark plug cables with a probe will damage the cables. The probe can separate the conductor and cause high resistance. In addition breaking the rubber insulation may permit secondary current to arc to ground.

- Connect the Red lead of the test tachometer unit to the negative primary terminal of the coil and the black lead to a good ground.
- Turn the selector switch to the appropriate cylinder position.
- Start the engine and let it run until operating temperature is obtained.
- With the engine at normal operating temperature (off fast idle), momentarily open the throttle and release it to make sure there is no bind in the linkage and that idle speed screw is against its stop.
- Disconnect and plug the vacuum line at the distributor.

Idle Speed Screw:

- Read the engine rpm on the 1000 rpm scale. If the engine rpm is at or below the curb idle rpm (800 rpm), proceed to the next step. If the curb idle is higher than specification, turn the idle speed screw until the specified curb idle rpm is reached.




- Aim the Power Timing Light at the front crankshaft pulley, or read magnetic timing unit. If flash occurs when timing mark is before specified degree mark, timing is advanced. To adjust, turn distributor housing in the direction of rotor rotation. If the flash occurs when timing mark is after specified degree mark, timing is retarded. To adjust, turn the distributor housing against direction of rotor rotation. If timing is within 5° to 9° (12° for high altitude), no adjustment is needed, proceed to step 10. If timing is outside specified tolerance proceed to the next step.

Distributor And Mounting Nut:

- Loosen distributor hold-down arm screw just enough so the distributor housing can be rotated in its mounting. Turn distributor housing until specified valve is reached. Tighten the hold-down arm screw and recheck timing. When timing is acceptable, recheck curb idle rpm. If engine rpm is not at or below the curb idle rpm, reset engine rpm and recheck timing. Repeat above until both engine rpm and timing are acceptable.
- Unplug and reconnect the vacuum hose to the distributor. Remove timing light or magnetic timing unit and the tachometer.