Those carburetors simply lack any adjustment for the opening rate of the secondary airflap. I'm told by an AFB expert that the flap is NOT designed for Pontiac engine power curves. My testing indicates that he is correct. No matter where we set the accl pump, or how much secondary jet was used, we could not get rid of the lean spot at the onset of the secondaries. Some mods helped, but the engine still hesitated/stumbled/bogged when we went to full throttle.
The slower the engine/vehicle speed, the worse the stumble. It was barely noticable at high speeds or at high rpms in any gear, and really bad from standing starts off idle. There is NO WAY that I know of to tune this out. Our answer was to ditch those carbs and go back to the Q-jet.....Cliff
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https://cliffshighperformance.com/
73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile),
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