[brown7373]

Okay. I popped the left side valve cover. Without turning the engine, none of the springs had obvious problems. I will rotate the engine at a later date to confirm the springs are not the problem.

I also got under the truck to make sure I had no heat riser on the exhaust manifold, and there is none. However, I think I found my problem. The number 1 & 3 plug wires were hanging down and very close to the exhaust pipe. One wire was split about 4 to 6 inches and the core exposed. It has been my perception that the noise I hear is coming from the left side, so I think the wires are the issue.

I am going to double check the valve springs while turning the engine, replace the valve cover gaskets, replace all the plug wires, distributor cap, rotor and plugs. It was nearing time for that anyway.

Thanks for all the ideas and suggestions, and I will repost when finished...hopefully with good news.