600 CFM vs 750 CFM...

roccodart - I don't know the Holley carbs, but I have to believe what I will say below holds true. The 600 CFM Edelbrock has smaller primary venturies and smaller primary bores. In all cases given one engine (say for instance my LA 360), the air velocity through the primaries will be greater. That increased air flow VELOCITY (not increased air flow, just VELOCITY) will have the potential to better atomize the available fuel.

Assuming both vehicles are tuned perfectly, the 600 would tend to crank up easier, and be better at low rpm (street manners). At what rpm the transition happens to where the 750 is better would be difficult to say. And I believe the transition would be so gradual, it would not be something a driver could say, "exactly 3275 rpm, the 750 is better." My meaning on this paragraph is, the lower the rpm, the more advantageous the 600 CFM would be (again, on one given engine).

For sure at WOT a bigger carb will have an advantage for bigger engines. On my Scamp, it seems to always shift by or before 5,000 rpm. And I would be "killing it" if I were to cross the line at 5,000 rpm in 3rd gear (not gonna happen). So ... I will never get to the point I need more airflow than a 600 CFM will deliver. The 600 CFM has the same secondary as the 750 CFM.

Quite honestly, with the 600 CFM, it feels like it is pulling harder at WOT. I had the 750 pulling 12.2 - 12.5 AFR's, and now I have the 600 pulling the same AFR's. With the 600 it "feels" stronger. The only reason I can contribute to that is the increased airflow through the primary side is atomizing the fuel better, and yielding more power.

A 600 CFM could be placed on the biggest big block around, and just around on the street it would drive like a dream. But on the drag strip, it would be slower.


7milesout