Stumped and Frustrated with a Holley 670 Hesitation

You're busy changing the big things,, but it's something small causing your prob..

Have you actually looked at the squirters and moved the throttle to see what's going on,, cuz you should be able to see what you are experiencing,.. There is a pause,, just a small gap where that squirter doesn't work..

I found it to be things like the needle under the squirter doesnt seal,, and the squirter circuit drains a litlle, causing a hesitation,, the metal strap that holds the check-ball in the pump cavity is loose, and allows 10* of throttle movement to close the check-ball, causing a hesitation,, a tiny bit of slack in the linkages, cause a hesitation,.. Something is causing a slight pause in the squirter shot,, you find that,, and you'll cure your hesitation.. Study it,, watch it's opperation, AS soon as you move the throttle, there should be an INSTANT and Continuous shot of fuel till you stop moving the throttle.!!!,

And that whistle is a gasket sucking air somewhere at high manifold vacuum,, check all the carb screws, baseplate screws, make sure the carb to manifold gskts don't leave a gap somewhere where they barely overlap..

hope it helps