I have a 350 Chevy that came with a 750cfm 4barrel Holley. This carb is just too big, and I'm done trying to adjust it to compensate, I got it close but it needs to be better. I was looking on Holley's website and using there interactive carburetor I came up with models ranging from 600-670cfm. If somebody could explain how much of a difference the 70cfm will make that would be great. In case you need to know- mildly modified Chevrolet 350, in a 79 camaro, with auto trans.