Setting the timing

  • 1983 GMC S15
  • 2.8L
  • V6
  • 2WD
  • 150,000 MILES
There is no OBD plug on this vehicle. I have removed the dash and searched everywhere, there is no tan wire on the passenger side under the glove box door mat or anywhere else. I need a photo of exactly where and what it is I need to disconnect to set the timing. I am desperate.
Thank you
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have the same problem?
Sunday, November 18th, 2018 AT 9:23 AM

1 Reply

HI and thanks for using 2CarPros.

Here are the directions specific to your vehicle. However, there are two forms of advance that were used. One is the traditional vacuum advance and the other electronic.


- Block wheels and warm engine to normal operating temperature.
- With ignition off:
- Connect timing light to number 1 cylinder.

- For vehicles with Electronic Spark Timing (EST) disconnect 4 wire connector at distributor.

- For vehicles without EST, disconnect and plug the vacuum line at the distributor.

NOTE: Vehicles not equipped with EST may be identified by the vacuum advance unit mounted to the side of the distributor.

- Start the engine, and aim the timing light at the timing mark. The mark on the pulley should line up with the timing mark. See: Ignition Timing > Electrical
- If an adjustment is necessary:
- Loosen the distributor hold-down clamp bolt at the base of the distributor.
- While observing the mark with the timing light, slightly rotate the distributor until the mark indicates the correct timing.
- Tighten the hold-down bolt, and re-check the timing.
- Turn off the engine, remove the timing light, reconnect distributor 4 wire connector or vacuum hose at distributor.
- Recheck Idle Speed, adjust if necessary.

NOTE: Disconnecting the 4 wire connector will set a trouble code and cause the check engine light to flash. After checking timing, check and clear trouble codes.


If the advance on your vehicle is vacuum actuated, there are no wires to disconnect. If it has electronic spark timing (EST), there will be a 4 pin connector to the distributor and another connector from the coil. I looked everywhere for a pic of the wiring, but found nothing.

If you can, take a picture of the distributor and upload it so I can see what you are dealing with.

The last picture I attached indicates ignition timing in degrees based on year.

I hope this helps. Let me know if you have other questions.

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Sunday, November 18th, 2018 AT 7:14 PM

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