I got a 1984 camaro z28. (carburated 350) I recently replaced a camshaft and lifters do to the stripping of intake lobes 4 and 6 (the lifters were also mess up haha) it went fine, we put the engine back together, but it doesn't accelerate worth a damn, and it backfires like crazy, at high speeds i can stomp on it and it will get up and go fairly well but if i accelerate anything above completly weak (i had traffic backed up at stop lines i was going so slow to avoid back firing) then i back fires and slows down horribly. A mechanic friend thinks its a vaccum leak, but i have a sneaky suspision its something worse, it had a leak on the exhaust manifold but we fixed it, what could this be????
help me plleeeaaassse.....
thanks

 

is it backfiring through the intake or exhaust?

i would say it could likely be a carb tuning issue. if through the intake (carb) you are lean, if out the back you are rich. i would also check your timing advance as that could cause it.

thats what i would do first.

 

Sounds more like timing. Did you set the ignition timing with a light when you put it back together? I assume this is the stock induction/ignition set-up, did you disconnect the flat 4-wire connector to the distributor base when you set the timing?

I assume you put the timing gears dot-to-dot when you put the cam in.

 

did you by chance maybe put the dizzy in 180 out when you installed it

otherwise i do lean to a timing problem, hard to say without the previous ?'s anwsered