if it won't idle, I'd say the culprit is a vacuum leak. This could also lead to a lean backfire.
I'd start searchin for loose, cracked or broken vacuum lines. If that doesn't fix it, then start sprayin carb cleaner around the carb, especially the vacuum lines and the base of the carb where it fastens to the manifold. If the engine speed increases when ya spray the stuff in that area, you've probably located the source of the vacuum leak.
Now my 64 C10 spits thru the carb....bit since it doesn't have a choke and it's a little cold blooded, I figger that it's just a lean backfire and I don't worry about it, cuz it goes away when it warms up. And it's gettin an electric choke AFB carb here pretty soon anyway. Like I might start workin on it tomorrow, if the good Lord's willin and the creek don't rise. Hmmm...I might actually have a hopped up 292 by the end of the weekend. How bout dat?
