Check your exhaust, see if it is clogged. Have you dropped the gas tank yet? Could be the filter sock in the tank is getting clogged as its suck gas through, then once it dies all the crapp falls off the filter until you run it again.
Could be, except that just doesn't happen all of a sudden. Engine ran fine and then started to show problems, and I doubt the rockers tighten by themselves. All vented, problem is there with out without gascap on the tank. Replaced the tank, pickup, line, fuel filter, pump and carb.. doubt that I have the same problem with all parts replaced. Simple single exhaust, plugged exhaust could definatly be the problem, this is a good one to check for we had dirt dauber nests in everything else. Checked and we have spark. Tank and all parts were taken apart and replaced as required, the tank and pickup, line, filter, pump and everything else are new and clean. Thanks for all the great input.. so far the most likely one is plugged exhaust.. that one I'm going to check soon.
Just a thought. Run it till it stalls, then check the float bowl. Is it still full, or empty. I once fished 3 shop towels out of a fellows gas tank. It would run great then randomly die off when one of the rags got near the pick up. Also try with the gas cap off to check for a tank venting problem.
The Jalopy Journal
