Fieri V6 Engne Timing

return to Tech Tips

How to set the ignition timing on a V6 Fiero

·         Correct timing for a V6 Fiero is 10 degrees BTDC.

·         Work only in a well-ventilated area.

·         Keep tools, equipment and body parts away from moving engine components.

·         Chock the wheels.

·         Place/keep the transmission in PARK (automatic) or NEUTRAL (manual).


1. Start the engine and let it warm up so that it goes into closed-loop operation.

2. Stop the engine.

3. Jumper terminals A and B on the ALDL connector in the center console behind the lighter       plate cover. (2 ea. T-10 Torx screws)

Notice that in the photo below the connector in the Fiero is upside down when compared to the layout shown beneath the photo.


ALDL Connector diagram 


You want to jumper the GROUND and DIAGNOSTIC TERMINAL pins (A and B).

 ALDL Connector
ALDL Connector Pinout


NOTE: Your harmonic balancer may have ONE or THREE Timing Marks. If it has three, use the center (wider) mark as reference.
I recommend highlighting the timing mark on the harmonic balancer a BRIGHT color so that it’s easier to see.

4. Hook up your timing light. We will start with cylinder #1.
Firing Order 

5. Start the engine. Point the timing light at the timing tab so that you are looking at the 10 degree timing mark and the center of the crankshaft is directly opposite.

Timing Mark

6. Record the timing.

7. Turn off the engine and move the timing light pickup from cylinder wire #1 to cylinder wire #4.

8. Repeat Steps 5 and 6.

9. Stop the engine.

NOTE: Example: If cylinder #1 is at 8 degrees and cylinder #4 is 12 degrees then, 8+12 = 20 and 20/2 = 10 degrees average.

10. Loosen the distributor hold down bolt (15 mm socket) slightly so that the distributor can just barely be turned.
Mark the distributor base to the engine block with chalk, Wite-Out or paint so you can reference back to square 1 if things don’t go well.

NOTE: Here is a trick you must use or you will get a great education. Use a short piece of wood or wear welding gloves to rotate the distributor. ANY leakage of spark voltage will do more than open your eyes.

11. Start the engine and try to set the timing of cylinder #1 and #4 so the AVERAGE timing is as close as possible to 10 degrees BTDC. You may have to check both cylinders several times while making small adjustments.

Don’t ‘fudge’ on this. Get it as close to 10 degrees as possible; the closer, the better. Take your time here and it will pay off in the long run.

Tighten the distributor hold down bolt and recheck the timing. The timing may move after tightening the hold down bolt.

If it is off of 10 degrees…start over. I can’t stress this 10 degree setting enough. 9.5 on one side and 10.5 on the other won’t get it right.

Remove the jumper from the ALDL and replace the cover.

Think I’m yankin’ your chain?

Engine Sticker

This article has been assembled by me using personal experience, the GM Service Manual, the Vehicle Emission Control Information label and, articles and photos from the Fiero community at Pennock’s and elsewhere.

No one takes any responsibility for any damages or injury except for you and you alone. Use good common sense and above all BE SAFE!

You are a part of the Fiero Community and we need you.

And never forget that the Pontiac Fiero was the ONLY other American car to scare the Corvette people…everywhere. Especially Chevrolet.


Roger the jolly