engine and drivetrain Firewall insulation on fire?

[02tom]

This happened awhile ago, but I've been wanting to put it on the FAQ so that if there's anything to learn, no one else has to waste their money. I had the car idling - the last time it would run a couple of years ago - and was trying to troubleshoot the injection system when I notice smoke coming from the back of the engine. I still can't imagine what I did wrong that the firewall insulation should start smoking and turn black where it was closest to the exhaust manifold. I'd driven it many times, and it never did anything like that. I don't have the heat shield for the tii exhaust manifold, but can't see that it should have matter much.

It's a shame, because now I'm looking at using the thicker aluminum piece from a 74-76 to cover up the area. Plus, it was a $50 part when I bought it that appears to have tripled in cost if I'm looking at the right thing.

51 48 7 450 110 - lists it as a "sound insulation"

[Davo]

I had the same thing happen once. The carburetor was running lean and it made the exhaust get very hot and the insulation strarted smoking. I changed the carb and never had a problem since. Since you mention you were working on a fuel problem, maybe you were running very lean?

[Davo]

One more thing I should mention is that the car I had the problem is was a 1974 so the thicker sheild may not help. I never caught fire but the smoke was pouring out from behind the shield.

The next day after changing the carb without doing anything with the shield the problem was gone and the car has been driven for months now.

[02tom]

Thanks, this helps to know this because it would probably be a wasted effort to install the 74-76 piece. I always thought the car was running rich because the plugs would get liquid fouled, but if the injectors weren't spraying correctly and just dumping liquid gas, it probably was running lean.

[SRC60]

Mine did the same thing. I was trying to get my tii to run decent and was adjusting the fuel and timing. Mine ran rich no matter how I adjusted it and I think I probably had the timing retarded to the point combustion was still taking place in the exhaust manifold which caused it to overheat the insulation.

Steve.