Not Ranked
I'm in agreement with a couple these responses... One, the accelerator pump cam may not be agressive enough to provide enough fuel when the throttle snaps open quickly. This will cause an over lean condition when the throttle is suddenly snapped open...too much air, not enough fuel...and a noticeable nose drop during hard acceleration. Holley sells a series of plastic cams, each with a different color to represent a different amount of gas injected via the squirters. Easy to replace, and certainly cheap enough. But, before you do that...check to make sure your squirters are working properly...like WTM442 suggested. I've seen much the same problem as you described occur when the screw plunger on the accel pump arm just wasn't long enough to fully depress the diaphram. A simple adjustment to the screw length was all that was needed.
Conversely, if you're going too rich when snapping open the throttle, you may be getting TOO much gas through the squirters....you may need to go to a less aggressive accel pump cam. If this is the case, you're going too rich...which, again could cause a noticeable bog under hard acceleration. I think the Holley kits come with 5 different plastic cams...Summit and Jegs both carry them.
And...Two.... I've never been a fan of vacuum operated secondaries. I'm running a Jet Performance tuned Holley 750 cfm 4150 series...their famous "Double Pumper"...no choke, mechanical secondaries. I've been very pleased with performance, both for street and track use. I can open the mechanical throttle linkage and butterflies by hand and verify that all four throttle plates are perfectly verticle when running WFO!!!
But...the best way to tell without wasting a lot of time, money, and effort buying and swapping carburetor parts is to go to a good chassis dyno operator and pay them for their diagnostic time. You'll be real glad you did...
PS...Here ya go....click the link and look at part number HLY-20-12... an assortment of 8 different cams for $21.95, plus more on the page to help confuse ya... 
http://store.summitracing.com/egnsea...+115&y=13&x=22
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Flyin_Freddie
"An opinion on everything...an expert at nothin'!"
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Last edited by Flyin_Freddie; 07-29-2008 at 03:31 PM..
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