Carburetor cfm calculator

273 said
True but a 440 runs fine with manifolds but headers are better for power, bet it would run fine with a with a 2 bbl at a cost to power, put a 750/850 on a stock 440 picks up a decent amount of power. Bet if you put a 390 4 bbl on a 440 would work better than people would think, My cousin Late Model 372 pulls strong to near 7000 rpm with a 500 cfm 2 bbl, carbs are pretty flexible. People could use the formula but they would be short changing themselves in power especially in a performance situation but they would definitely not worry about over carbing :)

I think carbs should come with 3 cfm ratings the conservative 1.5 hg for stock and maybe add something like 1 hg for performance and 0.5 hg for race.

The HP Holley's are rated at 2"Hg, so a 950 has 830 at 1.5", 1000 is 866 at 1.5".
Multi ratings are pointless, the only thing that determines the capability of a carb is at what flow rate it can maintain a standardized depression, that is how one can compare carb to carb. That doesn't compare quality of signal, metering, enrichment, etc. That job is up to Us, We use the products & evaluate them in the real world, and it's possible to bolt on 3 different 750's and have totally different performance/driveablity/efficiency characteristics...which one is for You & Your package? I know of a Guy that owned a machine shop that became so frustrated w/a Eddy Perf on His son's car, He took a hammer to it. Yet a friend of mine put a street TR w/2 of 'em on top of a 350 I did a set of camel-back heads for, only a Comp 280 Mag cam w/1.6 rockers, ran fine. 2 cammed 350 chebbies with over 9:1 squeeze, 750 on RPM & (2)500's on Eddy Street TR. Many variables there, and I have more of those, like a 440 GTX w/a 2x4bbl "low" intake w/2 600 Perf and it coughed and spit every time He nailed it. The pump shot didn't cover it, wasn't My project, but you could hear the weighted flaps snap open then back when it coughed. Yet again a member here had a pair on a smaller mill that worked for them.
A conservative goal and operation is better served with a like choice. Of course a 750 pumper will get You a better 60ft time, if You've got enough pump shot to cover the air stall, they always produce the best times. For a cruiser with occasional romps, how will one affect plug condition/life & mileage? Just sayin'.