The Stovebolt Site Forums The Shop Area Engine Shop 216 problem

Speaking from experience in this sort of stuff- I would first eliminate the simple things- weak breaker arm spring, breaker points improperly adjusted, wrong type of spark plugs, (old engine) excessive carbon and lastly if they are using the original valve springs, then I would check #6 for weak valve springs. This last one is usually what I have found to be what is happening. If it is running good at idle and misfiring when you rev it up, I would anymore just go straight to the valve springs.