Guys this isn't rocket science, all they are doing is comparing the CFM flowing through the motor @ a specific RPM and suggesting a carb that get's close. It will recommend a couple sizes if you are close to the edge of a range (and what they have available) and we all know how sizes will affect different parts of the power curve.

A mild 454 @ 4500 RPM would be just fine with a 650. Much like my stock 420 horse 502 which came stock with an 850 didn't need it.

EDIT: And also they aren't going to recommend someone else's carb, they will recommend what they have, even if it isn't otiimal for your set-up.

Anyway this has been beat to death, I'm going to go piss into a hurricane, much like a carb :)

what was the cfm rating of the quadrajet on the 454 mag?

[QUOTE=brivander;3540180]
A mild 454 @ 4500 RPM would be just fine with a 650. Much like my stock 420 horse 502 which came stock with an 850 didn't need it.
QUOTE]
It didn't recommend it for 4500 - it recommended it for 5100 rpm. At 4500 rpm 650 might be OK, but then you don't need a mildly modified 454 - a 454 truck engine will work.

Books I've seen listed 750 for the stock quadrajet. The Weber was 725 or 750, depending on source.

While a 650 would work, it's clear that a 750 will provide less restriction and more power - and having a 7.4L 300 hp merc with a weber, it doesn't hurt low speed at all.

Either that, or all the high dollar builders and thier dynos are wrong.