quote:The engine idles fine, but when I pumped the gas the bang turned out to be blowing out of the carburetor
I'm 90% sure it's carb related. Ignition and valve springs come later. Just had a friend's Pantera that did exactly the same, reason was lack of acceleration pump squirt. Check with engine off and a mirror over the carb (not your face) that you have two strong squirts immediately after opening the throttle. If you don't that's the reason. You can normally adjust it (my friend's Pantera was misadjusted by a mechanic, when properly adjusted the problem was gone). Or it could be dirt in some passages or a loose squirter (big screw holding it down, visible in the mirror).
A paste from my web page:
" it’s critical to adjust end play when throttle is fully depressed. If end play is too much you lose pump action, if it’s to little you end up destroying the pump. End play is determined by opening the throttle fully (engine off) and then seeing how much further you can press the accelerator pump at the are situated on the fuel bowl. You should be able to create a gap of 0.4mm, adjust spring just above to obtain that."