Timing

[Schurkey]

If your problem is the old balancer (damper) rubber having already slipped,

If it's slipped, it's DANGEROUS. That bigass inerta ring will FUKK-UP a radiator, shroud, fan, water pump--five pounds of iron, spinning at 2000+ rpm could be like a hand-grenade went off in the engine compartment.

UNTIL it flies off, it's doing a sub-standard job of absorbing the torsional vibrations.

the best bet might be to just reset the timing back to the 12 degrees you had originally.

I'm curious as to why the engine ran so much better with the timing advanced. However, at least try to put some science into this discovery--find out what the timing REALLY is. You'll need to verify the TDC mark on the damper by finding "true" TDC on #1 (or #6, but #1 is easier.)

I recall having the same problem and I did not bother disconnecting the EST wire. I think I just loosened the distributor and slowly rotated it one direction until I noticed the engine idle beginning to go down. I used a meter to check the idle. I marked that spot and then rotated the distributor the other way until the idle began to decrease. I marked that spot and set the distributor in the middle of both spots. It has worked so well for my old '88 Chevy, that I never bothered to buy a new balancer, even though my plan is to do so some day.

I can't even imagine what your timing is at higher RPM. Did you at least check the knock-sensor counts to assure the engine isn't detonating? IF (big IF) your timing is over-advanced, the knock sensor and electronic spark timing will retard the timing to eliminate the knock. But then, let's say you get a bad tank of gas, or it's exceptionally hot out--the engine detonates even more (but the computer is already at it's maximum electronic retard) There's no more spark retard available, and you pop the head gasket, or rattle the rod bearings out. If the timing is too retarded, you're throwing away power and fuel economy.

Timing an engine PROPERLY is SO EASY; and I bet you could buy a timing light at any pawn shop, or borrow one from a friend (Or just buy a new one!) Even getting one with the dial-back feature so you can map the timing curve at higher rpm is no real hardship any more; and hasn't been for thirty years.

Folks give me timing lights--they've bought newer vehicles where the timing can't be adjusted, and have no expectation of getting back into the hobby with an older car. I've got four of 'em; two I bought myself, two I've never tested. (On the "list of things to do".)

 

[kauila]

I'm curious as to why the engine ran so much better with the timing advanced. However, at least try to put some science into this discovery--find out what the timing REALLY is. You'll need to verify the TDC mark on the damper by finding "true" TDC on #1 (or #6, but #1 is easier.)

12 degrees might not be advanced at all if the outer ring with the timing marks has slipped that much.
I somewhat agree with your other points about it not being a good idea to let the problem go on as long as I have.

 

[PlayingWithTBI]

I recall having the same problem and I did not bother disconnecting the EST wire. I think I just loosened the distributor and slowly rotated it one direction until I noticed the engine idle beginning to go down. I used a meter to check the idle. I marked that spot and then rotated the distributor the other way until the idle began to decrease. I marked that spot and set the distributor in the middle of both spots. It has worked so well for my old '88 Chevy, that I never bothered to buy a new balancer, even though my plan is to do so some day.

I don't know how many times I can say

 

[kauila]

I don't know how many times I can say

It has not been a bad idea for me. I did that timing adjustment for my truck more than ten years ago. It has gone an extra 60,000 plus miles that way with absolutely no timing changes or any extra slipping.
I'm not worried at all about the inertia ring flying all over my engine compartment either, since there is a stout 8" diameter pulley attached to the outside of the damper and the inner diameter of the inertia ring can't be much more than 5" in diameter. I doubt that the inertia ring could even completely slide off the damper with that pulley in the way.

 

[PlayingWithTBI]

I'm not worried at all about the inertia ring flying all over my engine compartment either

I guess at 4000RPM that 5" ring that weighs twice as much won't get jammed between the serpentine belt and the lightweight stamped steel pulley and grenade under the hood?

Enjoy driving your time bomb

 

[Casey Price]

I guess at 4000RPM that 5" ring that weighs twice as much won't get jammed between the serpentine belt and the lightweight stamped steel pulley and grenade under the hood?

Enjoy driving your time bomb

Oh you know a broken crankshaft is so easy to replace. Changed my balancer last month. Truck runs much smoother and now the timing is correct.

 

[kauila]

A follow-up report on my '88 Chevy truck 305 engine with the "time bomb grenade" in it: I figured it might be a good idea replace both the timing chain and the harmonic damper, since the mileage is about 140K. It turned out that the original timing chain was stretched quite a bit, so I replaced it with an Elgin (SS-2100) timing chain set.
I replaced the old damper with a Pro Sport damper that they claim can safely go 12,000 rpm before any possible drama occurs.

I then checked the resulting timing to see if my previous method of setting it (without disconnecting the computer wire) was even close to being the correct timing of "0" with the computer disconnected. It turned out that my timing read 4 degrees advanced, which is pretty close . I'm thinking the computer may have made the adjustment for both the sloppy timing chain and the slipped inertia ring. I believe a sloppy timing chain would retard the engine a bit. I changed it to the correct "0" setting.

In any case, I must admit that the engine is even smoother than before and it goes like a bat out of hell. The engine is so quiet now that I can easily hear the TBI injectors clicking, which had me a little worried at first until I figured where the noise was coming from.

I also want to thank those who helped to persuade me that maybe it was a good idea after all.

 

[PlayingWithTBI]

Glad to hear you got it fixed.