Cfm?

[thirdstreettito]

CFM is cubic feet per minute. So when speaking of carb's thats cubic feet of air correct? I am guessing its sort of like a MAF, higher CFM carb means more fuel so it isn't running too rich or too lean correct? Thanks, Bradley

[monteboy84]

You're partially correct, cfm on a carburetor simply applies to the rated flow of the carburetor, it has nothing to do with how lean or rich the mixture is. Basically your need for flow in a carburetor is based on your entire motor system, and is directly related to the amount of air that the motor will flow, so for example a stock 350 V8 will require a smaller carburetor than an equivalent 350 that's been equipped with aftermarket high flowing heads, a high lift cam, a single plane intake, and headers, because the latter moves a lot more air. To adjust the mixture (rich/lean) you can change jetting to suit your particular motor, bigger jets to richen the mixture, or smaller jets to lean out the mixture.

This covers carburetor tech pretty well:
http://www.strokerkits.com/tech-info...cfm-rules.html

-matt

[thirdstreettito]

Thanks a bunch. Is it the same with blow-through carbs? I havent seen any below 600cfm. Do they use specific type jets or???

[NJSPEEDER]

With any blow through situation the regulation of fuel pressure becomes more and more important. Think of it this way, if you run your carb NA at a typical 7-9 psi that is perfect because there is no resistance. Once you add boost you need enough pressure to overcome the resistant force of the boost or the fuel can't get out.

The solution is generally easy enough, boost reference your pressure regulator and make sure you have a pump that can handle providing volume at the higher pressure.

-Tim

[thirdstreettito]

Thanks Tim, now to get money....