This issue with the engine timing really has me scratching my head.

So I rebuilt my 1985 2.5 liter I4 this winter and got it running this week. I resurfaced the head and had it bead blasted, ported the intake manifold and head, installed a performance cam with new timing gears, performance valve springs and new valves, new fuel filter, high volume oil pump and replaced all of the sensors and sending units. I put a MSD Blaster coil, new distributor (not the cap, the whole thing), high performance wires and replaced all the plugs and gaskets.

I double, triple checked everything, made sure the timing gears were installed correctly, and before I put the head on I installed the distributor rotor with the number one cylinder at TDC. It may have turned a degree or two when I pushed it into place on the block, but it was pretty much dead on #1 TDC.

I put everything else together, torqued everything down exactly to GM specs. I'm very thorough. So when the moment of truth came and I fired it up for the first time, I was really pleased at how quickly it started. Then I grabbed the timing gun and hooked it up and to my shock, the timing mark on the crank pulley was not even close to being inside the timing marks on the engine block. Since the top end of the scale is 12 degrees BTDC, I would guess it was probably showing around the 20-25 degree BTDC range at 1000RPM idle.

I freaked and shut the engine off. How could this be? I figured maybe I inadvertently turned the distributor before tightening it down. So I loosened it up and turned it before starting the engine. This time I started it but it ran noticeably rough, but I managed to get the timing to read at 8 degrees with some tweaking and satisfied I shut her down.

I went to test drive it the next morning and it took nearly 30 seconds to start, and the fumes in the exhaust were strong. It ran extremely rough and would backfire when you hit the accelerator. So I advanced it to where it read 10 degrees BTDC and took it for a spin. It stalled twice, had really rough acceleration, and backfired a couple of times. It would run smoother above 3000 rpm but if you had to slow down, forget it. I went around the block and drove back home.

I went over everything I did to the engine and then speculated that maybe the timing mark on the crank pulley was wrong, so I advanced the distributor back to where it was and holy crap, the thing ran like a champ. No knocking, pinking and the exhaust smelled noticeably cleaner. I took it for another test drive and it is still a little doggy at the lower RPM ranges (below 3000) but after 3000 it really KICKs the power in.

Now when I took this engine apart there's a few things I noticed. It was leaking oil everywhere. I just assumed it was because the engine had more than 100,000 miles on it. Then I noticed all of the seals were aftermarket, RTV mixed with cork everywhere and a lot of mismatched bolts and missing screws where stuff should be mounted. I'm am almost absolutely sure this engine has been rebuilt or might be a junkyard special. Which made me wonder if someone grabbed the crank pulley off of another Iron Duke off a Camaro or maybe a completely different GM car and slapped it on there.

I can't think of any other thing that would explain this. If this is the case, I'm going to have to keep adjusting the timing by shooting from the hip.

Anybody have any other ideas?

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Owner of:

1985 Pontiac Fiero Sport 2.5 liter 5 speed Isuzu
1986 Pontiac Fiero GT 2.8 liter 5 speed Muncie 282

Pull the number one plug, put a stick in the hole and find TDC of the piston. No matter what the pulley says, put a mark on it there for TDC. Mark 10 degrees advance, you can guess a little, it will still run OK. Now see what you really have, the marks on the pulley may not be based in reality. Larry

I'll give that a whirl next. I put it back to where it was when I first started it so I believe it's advanced probably 3-5 degrees as it is set now. Either way, I just assumed it was the correct pulley when I assembled the damn thing. Didn't think to check that the timing mark was corrrect it when I had the head off of it. I hate learning the hard way haha.

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Owner of:

1985 Pontiac Fiero Sport 2.5 liter 5 speed Isuzu
1986 Pontiac Fiero GT 2.8 liter 5 speed Muncie 282

[This message has been edited by Canyonflyer (edited 04-25-2013).]

Did you jumper the ALDL? You cannot set timing on a Duke unless you do that.

quote Originally posted by TONY_C: Did you jumper the ALDL? You cannot set timing on a Duke unless you do that.

I did not. I just reread the shop manual and I must have skipped that part last time. What effect will it have on the timing. Will it show that far out of whack if you don't do it?
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Owner of:

1985 Pontiac Fiero Sport 2.5 liter 5 speed Isuzu
1986 Pontiac Fiero GT 2.8 liter 5 speed Muncie 282

[This message has been edited by Canyonflyer (edited 04-23-2013).]

You have to jumper the ALDL for the timing to be set. The ECM will keep trying to correct the timing if you don't jumper it. After you jump the ALDL, check the timing on cylinder #1. Make your adjustments to get it where it's supposed to be (I forget what that is offhand). Then check timing on #4 cylinder and it if's different than #1, move the distributor to split the difference. Then recheck #1. When they are the same, remove the jumper and you're done.

[This message has been edited by TONY_C (edited 04-23-2013).]

I will give that a go once I'm absolutely certain whether or not the pulley is marked correctly. I still think the pulley is marked wrong, because ECM correcting or not, and with the distributor installed with the #1 Cylinder at TDC, I don't think it would have even started considering the timing mark was showing up on nearly the 12 O'Clock position which was so far off the scale it scared me. Just guessing by looking at the index on the block, I would say it was reading around 20 degrees BTDC at least.

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Owner of:

1985 Pontiac Fiero Sport 2.5 liter 5 speed Isuzu
1986 Pontiac Fiero GT 2.8 liter 5 speed Muncie 282

If it fired right up I doubt the marks or pulley is that far off.

quote Originally posted by Canyonflyer: I did not. I just reread the shop manual and I must have skipped that part last time. What effect will it have on the timing. Will it show that far out of whack if you don't do it?

I am guessing this is the problem.

quote Originally posted by TONY_C: If it fired right up I doubt the marks or pulley is that far off.

I'll give it a go tonight with the jumper in. I returned it back to the original position it was installed so without the jumpers the timing light is ticking way off the scale like it did when I first started it up. I did check the 1 and 4 wires when I did that and they showed the same timing. If this doesn't fix it I'll see about the timing marks.

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Owner of:

1985 Pontiac Fiero Sport 2.5 liter 5 speed Isuzu
1986 Pontiac Fiero GT 2.8 liter 5 speed Muncie 282

NP. Glad I could help