'86 Backfiring

My '86 backfires when I first start driving. Especially if I let off the gas from around full throttle. The backfiring actually blew the muffler out now and I don't want to put a new one on until I figure out the problem. I checked the timing and it's ok. Anyone have any ideas?

R or RE? read the plugs?

22R

is your carbuerator adjusted correctly? sounds to run rich or just extra fuel burning off in the exhaust..


but the whole muffler blowing out? sounds major

I think I almost have it figured out. My vaccum lines for my advance were crossed. I'm also runnning rich so once I get that adjusted I should be in good shape.

yeah backfiring is fun (to me) but i think running rich will have mileage suffer..

but i have a 22RE so thats a different story

So it turns out my vacuum advance module is messed up. The module costs $140 (WTF) or I can buy a new distributor that comes with the module for $100. Doesn't make any sense to me but I'll probably buy the distributor.

let me know if that module does fix it, because i thought the reason for mine backfiring was it running too rich...i love when ihappens esp when people are right beside the truck when i let off the gas...ahhhhhhhh good times lol