I've worked on one of those carbs for a friend who is using it on a 427 chevy. his had the hesitation/stalling thing too. I really changed some stuff around in it to smooth it out. with OOTB calibration his carb would not take off smoothly in first gear (4spd-4.11 gears). after changing things it would take off smoother in 2nd gear than it used to in 1st gear. after a going thru the carb drives and performs well; better than my expectations.


other factors may be timing curve; depending on camshaft. fuel pressure can be a factor too.