Ignition Timing: Adjustments

NOTE Timing specifications are listed on the Vehicle Emissions Control Information label under the hood. Always follow the Vehicle Emissions Control Information label procedures first before using the following procedure.

Timing Mark:

PROCEDURE
When using a timing light connect an adapter between the No. 1 spark plug and the No. 1 spark plug cable, or use an inductive type pickup. Do NOT pierce the spark plug cable. Once the insulation of the spark plug cable has been broken, voltage will jump to the nearest ground, and the spark plug will not fire properly.
Some engines incorporate a magnetic timing probe hole for use with special electronic timing equipment. Consult manufacture's instructions for use of this equipment.
On the V6 engine, the system will go into bypass mode by disconnecting the timing connector. This is a single wire sealed connector that has a tan with black stripe lead. On the 4.3L engine, this connector is in the cab where the Heater Box and the carpet meet on the passenger side floor.

The timing specifications for the 4.3L engine is 0° TDC.

Set timing under the following conditions:
- Normal operating temperature.
- Air cleaner installed.
- A/C "OFF".
- Transmission in neutral.
- Disconnect SET TIMING connector (tan/black wire) located in the cab where the Heater Box and the carpet meet on the passenger side floor. DO NOT disconnect 4 wire connector at distributor.

Connect timing light and adjust as necessary by loosening hold down bolt and rotating distributor. For specification, refer to SPECIFICATIONS/TIMING MARKS. Tighten hold down and recheck the timing. Stop the engine and connect SET TIMING connector. Clear control module trouble code by disconnecting control module power source or use bidirectional scanner.