Now that the popping was solved, I'm going to take a shot at why the dist.is causing the problem. First I think you will find something wrong with the mechanical advance weights. maybe a broken spring or a stuck weight. and possibility something in the vacuum advance system Its normal for your fuel level to change on a turn, but if you add an advance system problem on top of the fuel level the problem it could cause the problem. Just a wild guess. Gary Barker