Ignition Timing: Adjustments

NOTE: Refer to the Vehicle Emission Control Information Label located in the engine compartment. Follow all instructions on the label.


1. With ignition "OFF", connect the pick-up lead of the timing light to the number one spark plug wire. DO NOT pierce the wire or attempt to insert a probe between the boot and the wire. Connect the timing light power leads.

2. Jumper pins A & B together at the ALDL connector while not in diagnostic display mode. The ALDL connector is located above a hatch in the hush panel at the center of the dash. Jumpering pin A to pin B of the ALDL connector will cause the Climate Control Driver Information Center (CCDIC) to display "SET TIMING MODE".

3. Start the engine and aim the timing light at the timing mark. The line on the pulley will line up at the timing mark. If a change is necessary, loosen the distributor hold-down clamp bolt with special tool J-29791 or equivalent, at the base of the distributor. While observing the mark with the timing light, slightly rotate the distributor until the line indicates the correct value, see SPECIFICATIONS / IGNITION TIMING. Tighten the hold-down bolt and re-check the timing.

4. Turn "OFF" the engine and remove the timing light. Reconnect the number one spark plug wire, if removed. Re-install ALDL cover.

NOTE: DO NOT time the engine on seven cylinders since the unburned fuel could cause damage to the catalytic converter.