383 running REALLY rough.

[Steamboat]

Hey guys, I have a 58 Monterey with a 383. I had it in a shop, and one of the dudes there was revving it up, and he got on it a little more then I would have liked. When I left, it was running fine, but on the road It just started running rougher and rougher. Eventually it got to the point of where I was backfiring down the shoulder of the road, trying to get her to my buddies house. He checked the flywieghts on the distributer, and they were stuck, so he freed them, and put the distributer back in. Didn't help. We're going to replace the plugs, plug wires, condensor, and coil. The timing has been wavering back and forth, so we are going to cover all the easy stuff before we pull off the water pump and look at the timing chain. It doesn't seem to make sense that we are getting good spark, and the timing would waver like that. Any thoughts?

[430 6V]

Backfiring out the exhaust or intake?

Does it run smooth at all? idle or part throttle?

Any exhaust smoke?

I've seen timing jump around from cam movement or distributor wear etc, how much is yours jumping?

BTW I saw your car at the Billet Proof Depot Town pre cruise this last summer, neat piece.