- Connect a timing light and a tachometer in accordance with the manufacturers instructions. Never puncture the spark plug wires or boots with a probe. Always use the proper adapters.
- Start the engine and allow it to reach normal operating temperature.
- Set the idle speed.
- Put the transmission in Neutral.
- On models through 1980, disconnect and plug the vacuum advance line at the distributor. A golf tee or pencil usually works well for this.
- On 1981-83 and later models, disconnect and plug the vacuum hoses to the EGR valve and the distributor.
- Loosen the distributor hold-down screw just enough to permit the distributor to be turned.
- Aim the timing light at the timing marks on the case cover. As the light flashes, you will be able to see the timing scale. Slowly turn the distributor to align the marks at the proper setting.
- Turn the engine OFF and tighten the distributor hold-down bolt. Be careful not to move the distributor while you are tightening.
- Start the engine and recheck the timing.
- When the timing is correct, reconnect the vacuum lines.
- If the engine idle speed has changed, readjust the carburetor. Do not reset the timing.
- Remove the timing light from the engine.
- Connect a power timing light to the number one cylinder, or a magnetic timing unit to the engine. Use a 10° offset when required.
- Connect a tachometer to the engine and turn selector to the proper cylinder position.
- Start engine and run until operating temperature is reached.
- On 1984-86 models, disconnect and reconnect the coolant temperature sensor connector on the thermostat housing. The loss of power lamp on the dash must come on and stay on. On 1987-88 models, disconnect coolant temperature sensor connector. Engine rpm should be within emission label specifications.
- Aim power timing light at timing hole in bell housing or read the magnetic timing unit.
- Loosen distributor and adjust timing to emission label specifications if necessary.
- Shut the engine OFF. On 1987-88 models, reconnect coolant temperature sensor. Disconnect and reconnect positive battery quick disconnect (or erase the fault codes with sensor test #10 on 1987 1 / 2 -88 models), then start the vehicle. The loss of power (check engine) lamp should be off.
- Shut engine OFF, then turn ignition ON, OFF, ON, OFF, ON. Fault codes should be clear with 88-51-55 shown.
The only timing adjustment possible is injection pump timing. See Fuel System for the procedures.