One could put on a 2000cfm carb but it wont use that much unless it's the size of a D9 cat engine. An engine will only pump so much depending on the speed, valve timming and displacment. The volumetric efficiency is higher on some engines than others and the carb will be more efficient if sized for the engine. The engine will have to run with some manifold vacuum to operate the fuel flow, too small a carb and vacuum is too high, too large and the vacuum is too low. Air flow is rummored at 1.25scfm/hp at peak torque and 1.4scfm/hp at peak power. I don't know how accurate that is. Some look at accelerator pumps, float levels, clogged filters etc. when chasing an off throttle bog, quite often it's the fact the carb is so big the mixture is just too lean when the throttle blades are opened. Then we start putting larger jets in to compensate and the cycle starts. Ends up with bad gas mileage and exhaust that stinks like unburned fuel,


The Superflow dynos monitor airflow and process it into standard day readings, SCFM air flow.

I was wrong, again, the 455 only flowed 680scfm not 689 as I stated above. [attached]

I don't think you can go wrong using a 750 Quadrajet, you may not use all of it but you can also tune it to your specific build. Pontiac engineers couldn't put a different carb on each engine they made, true there are a lot of variants but not for every change of cam, valve,exhaust, c/r, piston etc. They had to have a one size fits most carb. And they did a pretty good job of it. We can choose and buid one for our specific engine. I'm looking at one from Prosystems based on a Holley 950HP they think it will flow only 830 true cfm. That's a far cry from my buddies 455 only flowing 680scfm in his 455. I don't think mine will use 830 cfm but the carb will most likely work better than the 800 I have now.