Well, I believe I found the culprit:



Notice how the metal ring has started to separate and pull back from the cylinder side, leading it to split.

Unfortunately (or fortunately depending on how you look at it), I uncovered another problem while inspecting the cam and rocker arms. The #3 and #4 exhaust lobes were all munched as were the rocker arms themselves. Looked like they had been hit by a grinding wheel that's how bad they look. So, I emailed EB and got a quote to replace all this stuff, and decided that I might as well go for the RV cam (the 270 version) while I'm at it along with new valve springs.

Darin-- tell me about this cam! <img src="/forums/images/graemlins/coolg.gif" alt="" /> Do you need to do anything else to the engine to make it run well? My motor is all stock, and all I have is a 2-1/4" cat back exhaust. Does the AFM need to be adjusted?

Also, concerning the head-- should I have it professionally cleaned, or should I be able to do that myself? I'm sure I can rent a valve spring compresser and completely disassemble the head. I just want to make sure I get everything super clean. I can inspect the head for flatness at work-- we have a surface plate here.

I'm sure I'll have more questions. You guys have been very helpful, and I appreciate it. <img src="/forums/images/graemlins/kewl.gif" alt="" /> So that's the update for now.