[markeb01]

I had this happen years ago on a Chevelle with a 350. Driving along near the end of a 3,000 mile trip and bang/pop and the engine quit. I opened the hood and found my distributor wrenched around a couple of inches toward the firewall and the distributor cap was shattered. The distributor was tight, so it had to be loosened to pull it back around to approximately where it belonged. The cap was taped back together with band aids. The engine fired right up and drove several hundred miles home, spitting and popping from the broken cap.

When I got home I changed the cap and set the timing and everything was fine. I never did understand what happened, but having experienced something similar I would look for anything unusual related to the distributor – cracks, arcing, something broken, maybe a hold down screw came loose, distributor clamp fully tightened, timing, etc.

If that doesn't turn anything up I'd probably do a compression check and/or test things out with a vacuum gauge to make sure everything is okay internally.