exhaust popping

i just finished my rebuild on my 400 pontiac. it makes a nasty popping sound after revving when you let the rpm come down. i firsst thought it was an incorrectly adjusted valve. i reset them and still no cure. i then figured maybe th ecarb was too lean but when i pulled a plug they weren't overly gray, maybe a even a little rich. im running a carter, crane springs and cam and headers. any suggestions. cars is perfectly drivable, its just annoying

Sounds like a small exhaust leak to me. In my car its right up by the manifold. Replace the exhaust donuts, check your pipes for holes/gaps and then check your carb. It may actually be a hair rich.

yeah that's probabbly an exzaust leak.

i ll try that 2 morrow. thanks for the advice

So did you ever fix the problem here? If so then what was it?

yeah it must have been a leak. put new header gaskets in and it was cured.