How to know what size carb to use? (Thread)

[patmckinneyracing]

I've been wondering this for a long time. I am running a 600cfm eddy carb right now and my motor has some good performance to it. But then I got my old man who has his 85 dodge pick up, 360 bare bones stock. Only thing not stock is intake and we took off all the emissions. He's putting a 750cfm carb on his bare bones stock truck but when I want to put a 750 holley on my car, he says it's too much carb... I'm lost cause my engine is making almost 2 1/2 times more hp than that truck. He went and kanked my carb off my malibu so he could "test" the truck because he has been having trouble with the thermoquad he bought for it. So how should I know what carb to use???

[Blake442]

There's a more complicated equation for it, but this is fun to play with, and is fairly accurate...

http://www.carburetion.com/Calc.asp

Or this one...

http://www.4secondsflat.com/Carb_CFM_Calculator.html

[megaladon6]

the true answer is that you don't know for sure. it depends on the engines relative efficiency and things like air volume, air velocity and usage.
IIRC you have a 350ci right? i'd say that the 600 is too small and to go to a 650-675, unless it's a race motor, then a 750 should work. 'course i prefer q-jets which can run over 800cfm, but act like a 600 at low volumes.
for your dads truck, since it's probably not running at the top end, i'd rather have the 600-650 range.