cfm ratings

[Marx3]

Hi, I have often been wondering what the primaries are rated at for different brands of carburettors? I mean 750/800 Qjet compared to "most-used" sizes of Holley and edelbrock.
I believe that even though a regular edelbrock is spreadbore, the size-difference between primary and secondary is not as big as om the Qjet...

Thing is I have a discussion going, and I claim you can go bigger, cfm-wise with a Qjet, than you can with a squarebore , say, Holley, without it hurting low-end.

[Schurkey]

I believe that even though a regular edelbrock is spreadbore, the size-difference between primary and secondary is not as big as om the Qjet...

While many squarebore carbs do have some amount of difference between primary and secondary, the "regular edelbrock" is a squarebore.

The Carter Thermoquad was a spreadbore.

Thing is I have a discussion going, and I claim you can go bigger, cfm-wise with a Qjet, than you can with a squarebore , say, Holley, without it hurting low-end.

Depends on the carb tuning abilities of the person involved.  There would be a tendency for a spreadbore to meter more effectively at the low end than a squarebore. 

[Marx3]

While many squarebore carbs do have some amount of difference between primary and secondary, the "regular edelbrock" is a squarebore.

The Carter Thermoquad was a spreadbore.

Thats what I thought... The primaries are not that much smaller than the secondaries, as far as I remember.
But for some reason or another, people tend to stubbornly claim that a Spreadbore is a Spreadbore.

Depends on the carb tuning abilities of the person involved.  There would be a tendency for a spreadbore to meter more effectively at the low end than a squarebore.

Ofcourse, goes without saying I guess, and that is the reason it would be very interesting to have some cfm-numbers to throw at the guys in the other end of the discussion.

A 750 Holley squarebore has 1.55 in. bore barrels, and a 750 Qjet has 1.37.  But the venturi design of the Qjet takes up much more space in the barrel, than the Holley's boosters. So maybe, on the primary side, the Qjet would equal a 650 or possibly even smaller Holley or Edelbrock...

[Marx3]

Anybody has any CFM ratings for the Primary side only?