I think I would try replacing the spark plug wires if you haven't already.Some how the shielding my be screwing with your spark. Are these custom made wires?
I'm rebuilding a 240 motor and need some help. I took my machinist my crank pulley and he said it looked scary. the embedded rubber was in pretty bad shape and he was concerned about its stability. I want him to balance everything but he thought I should try and find another pulley. I'm up for ideas. This is my first thread so I hope I'm doing this right.