Originally Posted by mjr46

first thing I'd do on that seeing the pic is set the idle air bleed adjustment screws, to do that you'll need a vaccum gauge and doing one side at a time you screw them in until car starts to die, then back out until highest vaccum setting is reached and as soon as you get that reading I usually go 1/8th a turn out more but not necessary, after idle circuit is set the best way to tune the accelerator pump circuits on holleys are they sell pump cams that are removable and different ones can be put on to change the delivery rate with lazyier or more aggressive ramps for quicker or more initial shot of fuel, also the squirters can be changed to a larger diameter ones to allow a greater discharge of fuel, usually hesitations that appear only on a throttle stomp like you explain, are related to a lean / flat spot, and are cured via accelerator pump tuning, that's to say the float level and FP is all set properly and all tune up parts are good and there are no vaccum leaks, also one thing I have done to cure some hesitations/brief stumbles on performance motors was to bump timing to 13-15 base

Originally Posted by mjr46

5.5 is a good place to set it at, you need to use a vaccum gauge to set idle bleed screws for accuracy, anyway, if the hesitation occurs on part throttle acceleration as I stated before I'd play with the accelerator pump circuit by either putting larger squirters on or change the delivery rate through pump cam switch to one with an initial quicker ramp on the pump cam