[/quote] Bowhay, actually there is a adjustment on a spring that controls the opening rate of the air valves ( the top set of butterflies) the bottom butterflies are mechanical, just like a holley double pumper, but the top set of butterflies (the air valves) control how much air that goes into the secondaries and how fast, its a bitch to set the spring properly trust me - you just have to play with it.
Too tight and they take to long to open up causing poor performance, too loose and they open to fast causing a bad bog but then takes off, sounds like yours are to loose.
And that pull off is associated with the choke, its needs full manifold vacuum on that hose, it disables the rear air valves till the choke has fully opened, if its not working or has a leak, the air valves may not open at all or open when the engine to cold to handle that volume of air.
Goodluck, Cp[/quote]
This is 100% correct. Due to the lack of a rear acc pump, you have to rely on the secondary circuits to pull the fuel. When his vacuum line was off, he went to a huge lean position, causing the hesitation.
I have been sucessful in running without the vacuum pod but tightening the spring on the upper butterflys. You had to be above 3500 to go WOT.
Dave