daveshea

This is a continuation of a previous problem I was having with my 87 coupe...

A few weeks ago, I blew the head gasket, and as a result, did a basic top-end rebuild while replacing the gasket. The valves and heads were all disassembled and cleaned, and all gaskets replaced.

When reassembled, I had a lot of trouble getting the car to run at idle.

I've gotten so far as to get the car to remaining running, though rough, set the timing, and was getting the idle set today...

While my friend and I were working on this, I was in the car keeping my foot on the gas to maintain the engine at about 1000 RPM so my friend could set the idle with the idle control screw. After maybe 3 or 4 minutes of running, with the coolant temp at about 175, my friend came back with the screwdriver only to notice the exhaust manifolds were so hot they were CHERRY RED!

How could this happen? We have never seen this before, neither before or after the work we did...

What has happened to make the exhaust manifolds that hot that fast?

Any insight you have would be greatly appreciated!
-David

1989TransAm

When I had this happen to me it was because the spark/ignition was to retarded.

daveshea

I believe we have the timing set with the EST wire disconnected set to 6 degrees before...

I was told that was the correct stock timing?

-David

desertmike1

did you leave a rag in the exhaust...try a vacuum gauge test to verify wheather or not there is a blockage in the exhaust system.

http://www.aa1car.com/library/exhaust_backpressure.htm

Sidney004

Check your cats; it sounds like they are toast.

SunCr

Huh? There's nothing you can do to adjust idle, but when you start turning that screw, you can screw it up. I'd guess you've stabbed the Distributor so that's it's off a tooth. Find top dead center on #1 and make sure the rotor is pointing at #1.

engle1147

What did you find as the "cause" of the first head gasket failure?



- guessing you were able to get the valvetrain preload reset properly -

Issues could be:
the distributor might not have been dropped back in on the correct tooth for the rotor's position
super lean (not enough fuel)
blocked/clogged exhaust
something got missed during reassembly process -(example) rags left in the exhaust system

PLRX

Do you have racing fuel in the tank?

daveshea

No, I'm not using racing fuel
No, there are no rags stuck in the exhaust

The original head gasket blew as a result of corrosion on one of the heads that created a small gap where coolant could get into the cylinder.

I believe the issue is that the car is running lean, but why or how?

Keep this in mind - the car ran absolutely fine before the rebuild. The problem has to have something to do with our reassembly work.

That's the problem - I don't know what we did or are doing wrong...

USAsOnlyWay

Is the EST reconnected?

daveshea

Yes, we only disconnected the EST while we were following the instructions for the IAC calibration and getting ready to set the idle via the idle screw.

The IAC was unplugged and the EST wire was unplugged, per the instructions for setting the idle via the idle screw.

We noticed the exhaust manifolds were glowing red and aborted the whole procedure...The manifolds got that hot within 3 or 4 minutes of running.

We reconnected everything and gave up for the day.

Cliff Harris

Vacuum leak?

bjankuski

This is your problem, the retarded timing is causing the fuel to still burn in the exhaust port and manifold. Don't hold the engine at 1000 RPM for 3 to 4 minute, the min idle procedure should only take a few seconds to complete.

The condition you experienced is normal with retarded timing. (yes 6 degrees is retarded, the car probably wants 30 degrees at idle)

JrRifleCoach

The "idle set screw" is not for setting the idle.
It sets the minimum position of the throttle plate. IAC controls idle speed.

You most likely have a vacuum leak.