I just put in a carbed 350 with vortec heads, and according to the guy i got the shortblock from, a 268h cam. Im running a holley 650dp on it and running about 16* base timing.

I hooked up the a/f gauge tonight and the mixture is good when its sitting and i rev it, but when its in gear under load and i get into the throttle a little it goes VERY lean and of course the car will stumble alot, then it'll recover and take off.

If i just ease into the throttle its fine. Im new to carbs but with my limited knowledge i figured it has to do with the accelerator pumps. Does this sound like it could be the problem? Can i adjust those by loosening/tightening the springs on them or do i have to change the pump and/or cam?

Oh BTW, its a stock carb. I haven't changed the jets or pumps. The primary jet is a 71 and the secondary is a 76

 

Sounds like you need to work with the pump cams, maybe the squirters.