Question about Chevy 292

[42chevy]

My cousin has an '82 Chevy truck with a 292. He has been having rough running issues. I have been helping and here is what I found. The distributor (an HEI) mechanical advance was rusted open and the springs were stretched out. We replaced the whole distributor to fix that. I noticed the distributor was making an arcing sound. On further inspection we found the coil was arcing to ground. I found that the coil was not grounding properly, it was missing a ground wire from the area where the power and tach terminals come into the distributor. I had one, just a short wire with a ring terminal on it. It still ran bad so we pulled plug wires and number 3 cylinder was dead. We did a leak down test and found a problem on number 3. He replaced the head with a reman and brought the old one by for me to see. The old head was fried , 3 of the exhaust valves were sunk into the seat about 3/8 to 1/2 inch! It was supposedly rebuilt about 10,000 miles ago. What would cause this to happen? No hardened seats? The arcing of the distributor and locked mechanical advance? We think the guy who "rebuilt" it used old parts he had lying around. What would you guys think? I will try to get pics to show what I mean. Also the valve springs on exhaust side can be compressed by hand, some of which I think is due to them sinking into the seat. Sorry for the mini novel.

 

[zzrodder]

The most likely cause would be the distributor - with it stuck in the advanced position, it would have run hot and been detonating and cooked the exhaust seats. Surprising it didn't burn the valves first - since it's an 82, it would have had hardened seats - I'd guess the valves were sodium filled since it's a truck, so that's why they didn't burn.

So how does it run with the new head?

 

[gasser]

could also have been a valve ground with to little margin, to much valve spring tension ,running hot at higher rpm,just a poor quality rebuild an cutting corners.

 

[42chevy]

It runs very well now except needs a carb rebuild. Huge difference in the smoothness of the sound and performance. I can't believe it ran as well as it did. I thought the distributor may have caused the valve issue. The valves were sunk to the point of being hard to believe. I am trying to get pics of it just to show how bad it is.