Need some help with confusing timing issue

[scsindust]

On my 89 in my sig, I hae tried to set the timing, but can't get it right. I know the PO put a reman'd motor in it. I found TDC on cyl #1, and adj the dist cap to line up with the rotor on cyl #1 wire. It seems it only runs good at like 20* BTDC. and when the EST is hooked up, it goes way back farther! So, do I try to get it so it is fixed and is set to the right timing, or just turn the dist cap till it smooths out? Which brings me to my next question: Whe I turn the dist cap, it runs best at the point when it idles the highest. does this sound right? It seems at its best that it still doesn't run 100%.

[68 TT]

Max advance will give you the highest idle but most times the engine won't start with that much timing and the ECM is making timing adjustments to compensate for knock.

Your best bet it to set the base timing with the engine off to give yo a fresh starting point to diagnose the issue from.

Pull the valve cover on the driver's side and remove the distributor cap.

Crank the engine over until the intake valve just closes on number 1 cylinder. Roll the engine over with a breaker bar and 5/8" spark plug socket on the balancer bolt until the timing mark is at about 8 degrees advanced (to the left of the zero mark as you are facing the engine). This will set the engine where it needs to be.

Now look at the distributor and see where the rotor is pointing. Make a mark on the engine where it is pointing then reinstall the distributor cap. Loosen the distributor mount bolt and turn the assembly until the number one spark plug terminal lines up with the mark on the engine you placed where the rotor was facing. Tighten the distributor back down.

It should now start and have close to the correct amount of base timing. Leave the brown timing set wire connection apart and start the truck. It should run well enough for you to set the timing with the light to the factory specs for your truck.

Connect the brown wire connector so the ECM can now control the distributor again and start the truck.

If it doesn't run right you may have a mechanical problem such as a worn out timing chain set that has allowed the chain to skip a tooth on the cam gear or an issue with the electronics / ECM. If it's not tripping any codes it is probably not in the ECM.

I have seen this before where the vehicle ran poorly and the timing was impossible to set to make it run right and it turned out the timing chain skipped a tooth. It sounds a little like your problem but I hope it is just a timing issue.

Hope this helps.

[old Rusty C10]

i had the same exact problem with my non ecm 1982 and it was a timing chain

[scsindust]

The PO told me there was only a few thousand miles on the engine when I bought it, so I'd hope it isn't the timing chain! As soon as the weather breaks, I'll try timing it like you suggested. Its been in the 90's for the past few days, and it is hell working outside in the sun with these temps.

[1985-GMC]

Originally Posted by scsindust

The PO told me there was only a few thousand miles on the engine when I bought it, so I'd hope it isn't the timing chain! As soon as the weather breaks, I'll try timing it like you suggested. Its been in the 90's for the past few days, and it is hell working outside in the sun with these temps.

90's that must be nice, its 96 today here in texas and this is a cool day.

Tony

[68 TT]

Around here a few thousand miles means 100,000+ but it's been freshly steam cleaned.

Without paperwork for a rebuild a PO's word is worth zero.

[scsindust]

i'd take a 96* day in Texas over this any day! Texas doesn't have the terrible humidity we have up here. 92 right now with 60% humidity, makes it feel like over 100 and makes you sweat so bad!

[scsindust]

Ok, so I tried what you wrote down, and at 8* it barely runs. I mean it sputters and idles like it has a wicked cam. I only runs like that for maybe 10 secs before it stalls. It runs much better at a little over 16* base timing. If I set it higher it idles a bit higher. I only test drove it at 16+*, and when i hit it up it had no power, so 16+* isn't right. Idon't really know what to do right now. I guess I have to have a local mech check it out??? (sigh)

[68 TT]

That sounds like you have a vacuum leak. Get a vacuum gauge and see how much vacuum you have.

In stock form you should have around 20 to 24 inches of vacuum at idle. Much less than that and you have a leak somewhere.

After you find & fix the vacuum leak if it has one use the vacuum gauge to set the air & fuel mixture screws on the carburetor so you get maximum vacuum. You will have to go back and do them a second time after setting them both as the adjustment of the second mixture screw will throw off your setting on the first a little.

As a sanity check on the timing chain please turn the balancer bolt with a 5/8" socket until all the slop is out and line up the timing mark at zero then turn it the opposite direction until you feel the slack in the chain fully taken up. See how many degrees on the timing mark it has moved. If it is more than 4 or 5 degrees you most likely need a new timing set.

[nlped]

If it is an '89 wouldn't it be a TBI? Pardon my ignorance

On another note...It's 97 degrees out with 90 % humidity which puts the heat index at about 4000 degrees...I'm melting!

[68 TT]

Unless it has been modified it is TBI. I didn't remember him saying what year it was and just assumed it was carbureted like most squares.

TBI's are prone to base gasket leaks so that would be a good place to start looking for a vacuum leak if it has one. I just fixed one on my friends 91 Suburban and had one on my 90.

[scsindust]

The heat index today peaked at 105. Anyway, it is a TBI. I'll start with the vacuum. I thought vacuum leaks made it idle high?

[nlped]

Thanks for clearing that up 68 TT. Now, I have to agree with you on the timing chain issue or could the distributor be a tooth off (counter clockwise)...which would explain the need for so much advance, right?

[scsindust]

If the dist is off, then i would just have to turn the dist that much farther to make it work at the correct *.

[nlped]

^^^true!

[68 TT]

If the rotor is not pointing to #1 at TDC then the timing light will show an incorrect number so you can't go by what is says. Check that first. It could be as simple as that. Rotor phasing could be way off.

Line up the timing marks and pull the distributor cap to see where the rotor is phased relative to #1 spark plug terminal on the cap.

I take a sharpie and mark the distributor base where the #1 plug wire terminal is located so with the cap off you always know where it is.

After you set your base timing correctly you can mark the distributor base & intake with alignment marks too so you can quickly see if the distributor has slipped out of phase down the road.

I have had more than one vehicle that the distributor clamp was bent out of shape and when fully tightened down did not completely secure the distributor in place well enough that it couldn't rotate on its own. Once you tighten the bolt down make sure you can't easily turn the distributor with your hand.

[68 TT]

If the distributor is off more than a couple teeth you may not be able to turn the distributor far enough to get it back into alignment with #1 without the wiring being stretched tight.

My plug wires don't have much slack in them with the way they are routed through the wire looms so I have to be pretty close on how the distributor is installed.

[68 TT]

Originally Posted by scsindust

The heat index today peaked at 105. Anyway, it is a TBI. I'll start with the vacuum. I thought vacuum leaks made it idle high?

A small vacuum leak will raise the idle but a big one will make it run rough.

That just reminded me of a strange vacuum leak I once had. The top of the plastic adapter for the hose connecting to the power brake booster came off and caused a huge vacuum leak where the engine would barely run.

[nlped]

I came up with the tooth off idea because I had to pull my distributor out yesterday because the PO broke the rear Dist. cap screw off in the Dist. base. When I first put it back in I missed by a tooth and had a med./high rpm "pop". I double checked the distributor and moved it 1 tooth forward and reshot the timing and all was well. It was just a possibility, but I am no driveability expert.

[Desert1957]

I would make sure there is no Vacum leaks as mentioned in the other post first....

Here are some other things to check , If you don't know what year engine you have. I would start there, some late 80's engines had the timing pointers up behind the water pump (like at 12:00) , pre 86 small blocks had the old style down on the driver's side. Timing pointers are like 30 degrees different or more. some one may have used an older engine with a new cover. Or a newer engine with the old cover , this would account for the timing mark be up off the scale for the motor to run correctly.

Something else too , older SBC's ar famous for the ring on the outside of the balance turning. timing mark could be anywhere if this happens. Only real way to check this is to remove the Balancer with a puller and see where the keyway slot references the timing mark.

Desert

[68 TT]

Originally Posted by Desert1957

Here are some other things to check , If you don't know what year engine you have. I would start there, some late 80's engines had the timing pointers up behind the water pump (like at 12:00) , pre 86 small blocks had the old style down on the driver's side. Timing pointers are like 30 degrees different or more. some one may have used an older engine with a new cover. Or a newer engine with the old cover , this would account for the timing mark be up off the scale for the motor to run correctly.

I just had to deal with this on my wife's Malibu. PO used newer accessories & timing cover / balancer on an older engine. The crank keyway is in a different location so the timing shown with the light was way off.

[scsindust]

here's a question for you all: do you guys take the air cleaner off when you adjust the timing? You almost have to to get to the dist. I assume this wouldn't hurt the vaccuum? I'll get the engine numbers and post the info I find about them so you experts can guide me!