Everybody that I've heard from has said Holley carbs normally run real good right out of he box. I really don't know what sizes the come in but I would say you should be good around 500-650cfm. Something wrong with the Holley you have? The motor is only going to use as much fuel as it needs. If your Holley is in good shape it should be able to be adjusted to run fine on your motor. Ask around to see if anybody in your area is good with carbs. Probably only take a few minutes to tweek it or drop some smaller jets in and you will be good to go.
