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Max CFM on Quadrajets is somewhat misleading, since GM sometimes used the same carburetor body for multiple cars, and made small tweaks and mods to change its performance potential. Most of the newer Quadrajets can flow up to 750 CFM, and some are closer to 850 CFM maximum, but GM put limiters on flap opening, smaller jets, etc. so they would flow more like 600-650 CFM max. Since all the mods work together to get a good running engine, tuning and getting it all working effectively can be frustrating.I like Quadrajets, and I'm currently using one on my 350, but for a new purchase there are probably simpler options. The Edelbrock 1406 is a favorite because its simple, and usually only needs idle mixture and step-up spring tuning to get it running smoothly. And that tuning can be done with it still mounted on the engine and the top still on the carburetor. Another favorite is the Holley 4160/4150, and there seems to be many folks out there who know how to tune them. Holley also has several good high performance carburetors, but prices go up quickly when you go to the Dominator series or the Ultra XP.Bruce