327 chevy with a carter abf 625 stumbling while driving?

Question

I have a fresh rebuilt 327 chevy newer style heads 1.94 intake valves with a little better than stoch cam. streetfighter intake (eldbrok) with a carter abf carb. the secondarys are progressive with the throttle linkage (not vaccuum) but it has this funny second set of butter flies in the secondarys. on normal accleration it works pretty well but give it a liberal dose of gas and is stumbles which is either a vac. leak or too much fuel. also while driving at highway speeds it sputters until you give it more fuel and it clears up. so while not acclerating it stumbles a tad and giving it the gas it clears up. It has a point system on it which I want to change but do not have the money for right now. timing is right on the money and cam timing was dialed in perfect (degreded in ) It had a rebuilt holley but that proved to be a bad carb. after the engine has ran a while it also is very hard to start, I'm sure its flooding even buy not giving it gas. any thoughts! thanks

Answer 1

Check to see where you have the vacumn for the advance hooked to . The point style distributor only gets vacumn when gas is pressed . If there is constant vacumn at an idle , there is part of your problem . That will also create a vacumn leak which will screw up the carb .

Answer 2

You have to ask yourself some questions.

Was the problem with the last carburetor similar? If it was, then the common denominator is the engine. Either it needs to be tuned or the timing has to be set.



Idea: Pull the spark plugs after you've run it, How wet are they? Do they smell like fuel or do they have a carbon smell to them?



You also mentioned you have an old school point distributor, you might not be burning the fuel properly due to this old system. Is the advance on the distributor working? Hope these questions and ideas work for you. Good luck.

Answer 3

Sounds like a vacum leak...You need to put a vacum guage on your carb to find out...You can also spray carb cleaner around then carb and manifold to find out...

Answer 4

Sounds like a timing issue especially with it being hard to start after being ran for awhile.