Originally Posted by Nemeth
Hey guys I got a 670 Avenger vac secondaries that i cannot get the secondary hesitation out. 383 sbc 180 cc heads,236/242 @ .050 duration 2500 stall 700r4, 373 gears. Maybe a 750 mechanical ???
Often, secondary hesitation is caused by a too-quick opening rate. When that happens (too quick sec. opening) there's a lean "hole" in the air/fuel delivery. The way to counter this is to either slow the secondary opening rate (usually works best), or try to extend the accelerator pump shot to cover the lean hole.
There are several ways to tailor the secondary opening rate of a vacuum secondary Holley, but the first thing I recommend is to use the next stiffer secondary diaphragm spring and note the results.