Poping through exhaust

[BULLDOG]

I have a Goodrich crate engine with a Edl performer and a Edl 600 carb with headers and when you let off the gas it pops through the exhaust.

Anyway I can stop the poping?
 

[Grim 82]

Yeah, just don't ever let off the gas
Sounds like it might be getting too much fuel or not enough timing advance, or a little of both.

[topp]

A small exhaust leak can also cause that....

[VileZambonie]

Check the basics first,

No vacuum leaks, plugs gapped right, wires, cap & rotor, timing, firing order etc. If OK start with a compression test.

[BULLDOG]

Well its when say you are coming into a stop light and you let off the gas and dont push in the clutch it pops ,so I think I will plug off the vac ports on the carb and see if it still pops.

[onelow84]

x2 on exhaust leak possible

[1979C20]

You said you have headers, but what do you have for exhaust? I have a manual tran too and headers with glasspacks right after that dump out in front of the gas tanks, towards the ground.  When I let of the gas in any gear, or downshift, it backfires quite a bit because there isnt much back pressure. so what do you have for exhaust?

[BULLDOG]

There is flexible pipe coming off the back of the headers and 3 feetish of pipe and then a thrush muffler on both sides.

[VileZambonie]

You need a real exhaust system or it's going to sound like a garbage can with firecrackers blowing up inside it. Have an exhaust shop make a secure connection from the collector to the pipe.

[Psycho71]

My '71 has a short exhaust system like the OP describes. Short offsets from the headers to the 40series flows, then turns down from them right behind the cab. It would "back-pop" horribly when deccelerating. I put in an H-pipe and it quit. The mufflers still drone like crazy, that's another matter entirely, but no more popping what so ever. I guess allowing the banks to equalize fixed the popping.