This is a reasonable assumption. Looking back through the thread, you didn't show any evidence of excessive fuel dumping due to injector problems either (which would create black smoke and potentially backfiring).

OP: The problems (with timing) started when you first pulled the opti, there is evidence that something shifted because timing never gets ATDC in the timing table. Also, when you measured physical timing (at 40) vs ECM timing (at 26), you showed a 14 deg descrepancy between the actual timing and where the computer THINKS it's timed.

That points to a harmonic balancer that's failed OR a "distributor" that's off a tooth. But you think the opti is oriented correctly. I wonder if the harmonic balancer was the original problem...and somehow aggravated by the r/r of the opti? If you physically retimed it after r/r of the opti, it really COULD be off.

If the damper's bonding has failed and it is "moving around", I suppose you could also have gotten it retarded enough to have it timed where the manifolds got hot...especially if you "retime" an engine with a failed balancer (damper).

This doesn't account for the discrepancy in your two optis...but if one is manufactured wrong AND you were off (at least once) when checking or physically retiming it, maybe the OTHER opti is throwing you far enough off to cook the manifolds?

 

It won't? That COULD be as much as 50 degrees off -- if the timing is really SUPPOSED to be at 40-deg advance when running 1200 rpms.

At idle, my stock 89 bin shows 40ish at 1200rpm. (It's a bit tougher to tell by the LT1 graph...but it looks like 36-37....which is still a long ways from 10 ATDC.)

BTW SELLC...load and rpm ARE used to access the correct values in the timing map. You are correct about that. However, if you install a cam other than "straight-up", THEN set the timing, THEN program the computer so it "knows" where the opti/dizzy is set, THEN tune it by setting fuel/timing tables (based on knock and AFR), the engine won't be "off". Everything will be living in it's new "equilibrium". This is what that other discussion was about.

In this case, the OP might have disturbed this correlation if the damper has shifted and it was reset to a false location created by failing bonding in the damper. Guessing vacuum would cause the timing to shift all the way into ATDC values doesn't seem possible.

The big "mystery" might involve all of the things that happened before the point this thread begins.

 

I don't think so.

Back in the days of the carb and mechanical advance distributor, I seem to remember making more than a few blunders trying to adjust the advance curve. I used to want 36 degrees "all in" by 3000 rpm. On one special occasion I literally misunderstood which tooth on my timing pointer I was supposed to line up with the balancer mark. My only real symptom was that the coolant temp was about 25 degrees higher then it had been before I messed with it. It didn't even really seem all that down on power. By the time I figured it all out I realized my base ign timing was at least 10 degrees ATDC. I had been driving the car around that way for a week. I realize times change and so have the cars but the relationship between TDC and the instant the spark plug fires will never change.

Fast forward to when I knew what I was doing in the mid 90s and worked in the highest fleet car volume dealer in Mi. Specifically "B" body cars sold for use as police cars. One unique problem with these cars was that you could not buy an engine assembly for the caprice police car. You had to buy the caprice engine and replace the camshaft. Well every so often an inexperienced heavy repair guy would assemble these things with the cam sprocket off one tooth. Its an easy mistake to make when your just looking at the timing dots on the sprockets. They almost line up. Anyway, after the newly installed engine wouldn't rev past 2000 and the cast iron manifolds were cherry red within 30 seconds of run time the heavy repair guy would be totally mystified....until they installed the cam properly.

So anyway,that's why I think what I think. Could I be wrong ? Of course I could, but between then and now, I have yet to see any set of circumstances that will cherry red the manifolds besides the cam off one tooth. Maybe I'm going to learn something on this one. I hope I do. As the OP is finding out presently; there is nothing worse than wandering around in a metaphorical "dark room".

 

The crank hub has an alignment mark on it.
That mark is pointed straight to the cam drive hole when engine is TDC #1.
It is keyed to the crank. It cannot move.
When I put the pulley/balancer back on, I always put the hub straight up(by turning engine), then put the pulley straight up also.
The timing mark I am using is a mark I put there myself.
I have 2 different marks now.
One to do timing with the waterpump off. One to do with pump on.
It has not moved since I have been doing this.

Thank you for the "my engine does this info"
And the "this happened before" story.

I am going to drop oil pan and remove timing cover.
I gotta have a look.

 

Oil pan and timing cover is off. What a job.
Has anyone ran into the situation where a GM engineer has put an elephant in the way of another part of the car?
Seems like that is how it goes.
To check timing chain, timing cover needs to come off, to do that, oil pan needs dropped, to do that oil filter gallery,starter, and trans cover needs to come down. Oh yea, don't forget the oil level sensor.
To remove oil filter gallery, cat needs to come down.
Then when the pan is down, back to front. Water pump needs removed. Balancer and hub needs removed. To do that, motor mounts need undone to lift engine. Then custom make pullers for pulley and hub...Then the opti.


And all for nothing... Timing marks are right inline where they should be.

 

Gawd damm what an unbelievable pain in the azz. Well all you can do at this point is take your time, and carefully reassemble everything so as to be certain there won't be any leaks. Your picture clearly reveals zero problem with the timing chain. I hope by the time this mystery is solved it's not somthing stupid like a crossed plug wire at the distributor.

 

Not much help but I was fairly certain the hub is NOT keyed on the crank and the alignment marks shouldn't be trusted on the hub. From what I remember they are press fit

 

Did you check your cats being plugged before you decide to tear it apart?

 

It's the damper that is not keyed. The gear is keyed and essentially has to be.

 

The hub is press fit.You are/were right.
I assumed it was keyed.
No. I tore the front of engine and old opti apart before I found cat problem.
I am getting more lost.
At least I have some new parts that are pretty important. Oil pump and drive, and timing chain. Trying to stay happy. New seals on front of engine.
She is almost back together.
I will make new TDC mark.
I still don't understand why the opti that is aligned early fires late, and the opti that is aligned late fires early.
There are things going on that I don't understand.

 

After typing the last message, I am wondering.
Could the old opti been sooo far off that the #2 spark was going to the #1 ??? and the #1 was going to the #8 ???
The computer with the old opti was trying to push the timing more advance. To 38 ? But it was 10ATDC.
Could this, along with the misalignment made it hit # 2, but way late ???

 

It won't run if the distributor is so far off that spark is jumping to the next cylinder.

Can you TDC #1 piston, firing, then stick the opti on there w/o the cap and see if the rotor is pointed at #1 post?

EDIT: Never mind...you already did that. :/

 

Yes I did do that. The opti was not off a tooth. I think It was made wrong.
It is sitting between #1 post and #2 post while piston was at TDC.
As I said 2 weeks ago. I cant believe it was even hitting the pin on the cap while the coil was firing.
If you take this misalignment, then add 36 degrees of advancement to it... I think it was firing soo early, it was firing the wrong pin.
The opti that was aligned early(wrong) was the one firing late at 10ATDC with an advancement of 36.

Let's assume I am right on this.
The engine ran before I took opti out.
Could the timing table been changed, either by a programmer, or the computer itself knowing somehow?
I unhooked the battery to change optis the first time.
Could the adjusted table got changed somehow? Went back to a "starting point" table???
Is this even possible???

 

The ECM can't/won't change anything on it's own. Someone could retune it of course, but no way it will change it's own timing, from swapping opti's. There isn't a way for it to know that anything has changed b/c the opti provides all of the info. There isn't another input for it to "compare" or calibrate itself.

 

I'm not sure what's causing your problems, but maybe it's time to widen the scope of your investigation.

cherry red exhausts = raw fuel being burned in the exhaust manifold ? and not the result of timing chain being out of synch? maybe an exhaust valve is hanging (stuck) open or a rocker arm has come askew and is holding the valve open. I think it's time for a compression test and pulling the valve covers to see if anything is amiss there.

 

Compression at 192-195 on all.
The new opti does not overheat the exhaust.
Just the old one I removed and reinstalled.
I didn't know If knock sensors were always seeing detonation at say 15 BTC. Would the ECM adjust permanently.
Knock sensors are a way ECM could know something.

I got coolant in and air purged out.
She runs great.
Starts at 1200 RPM and climbs to 2000 rpm as she warm up.
I did not check timing.