600cfm or 750cfm? That is the question??

myasylum said

Man, this is crazy! it's just all over the place. So much for a easy answer! :)
Basically stay away from the 750 Edelbrock and everything will be fine.
I'd get a Quick Fuel if it were cheaper. That street avenger 670 cfm does sound like an option...
How many Hollys are there???? There are quite a few to choose from. Which one is the good one? Avenger?

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What type of engine is this carb going on? A hot-cammed street/strip engine, or a milder street-driver one? I used my buddy's 600 cfm Edelbrock Performer on my 318 and it worked fantastically, but of course the carb I swapped off was a POS ThermoQuad.

The Performer is based off the Carter AFB while the Thunder is based off the AVS. They are basically the same except the AVS has an adjustable spring-loaded secondary air valve while the AFB's is non-adjustable and operated by counterweights. The only thing the adjustable one helps with is letting the secondaries start working sooner (NOT opening, Edelbrocks/Carters are all mechanical secondaries with a vacuum-operated air door) or later, which helps the engine get its fill at the correct time.

A Holley will drive great and have great performance but they are not sophisticated enough to get the best possible gas mileage for more street-oriented engines (unless of course you're talking about the Street Avenger series).

Since I'm guessing your engine is over 400 cubes I'd recommend a 770 cfm Holley Street Avenger or an 800 cfm Edelbrock Performer OR Thunder series (preferably Thunder just because of the extra tune-ability).