[Russ Noble]

So John, is this a new OTB carb or secondhand? What jets and needles are you running? What happens under 2000 rpm? Is the hesitation just an initial stumble when you floor the pedal or does it run rough all the way through to 4000rpm?

I am no expert but I have found my 500 Edelbrock on a Rover V8 very tolerant to a range of engine capacities, 215 to 300 ci, single and dual plane manifolds and mild to not so mild cams. Always runs well with OTB jets etc, just needs small changes to optimize everything.

I don't have any experience with Holleys but the Edelbrock does not seem difficult to deal with if you follow their supplied handbook and apply needle and jet changes diligently using their reference graphs. These are also available online.

Are you sure it's your carb, and not something silly like the cam timing set incorrectly etc?

Cheers