This is driving me crazy. The 1 bbl carburetor on my '63 coughs and sometimes backfires. I had it rebuilt by a very competent mechanic, but, he is off protecting our country right now, so he can't look at it. It happens every time I "aggressively" step on the gas. If I slowly accelerate, it purrs. What gives?
Oh boy! I had the identical problem you are talking about. Although it might not be the same cause, but you are running lean. Dollars to dougnuts you have an intake leak or vacuum leak. I had a pretty good intake gasket leak. You can check for the leak by using carb cleaner. Spray it around the intake runners, carb base gasket, etc and listen for the engine to speed up. You can also use raw propane I have heard but dont know how well that works. I had a piece of old gasket on the manifold that I missed when I replaced it. Try this and get back to me! Nik
That is definately a lean situation, something is leaking air, check your carburetor base plate to body screws, see if you can wiggle it sometimes they come loose.
my 66 k-10 does that also. i advanced the timing and it stopped. its due to the timing chain stretching. put a new timing chain kit or try advancing your timing first to see if it stops.