It's not just a matter of matching up numbers to numbers when selecting a carb and then deciding one is too big or too small. On a stock 250 a 390 Holley might be too much and yet on a well built up 230 a 500 Edelbrock might not be enough.
Things like compression ratio and volumetric efficiency compound the situation along with everything else that has been done to that engine.
Another thing you have to consider is just how often and for how long will the engine be running wide open at xxxx rpm and actually trying to gulp down 390, 500, or 600 cfm? Reality is that most of the time the street engine is being operated on its primary throttle plates and the total cfm of the carb is not a factor. Only at wide open throttle will the carbs max CFM become a factor as to the engine getting too much or not enough air and fuel.
I believe most people are giving you their real world experiences as to which carb works best on their engine. Don't let only numbers be the final decision when selecting a carb.
Mike
