[Tom Vaught]

Now we will compare dimensions on the two "500 CFM" Rated carbs.

#4412 carb has 1.375" venturis and 1.6875" Throttle Blades.
#4783 carb has 1.5625" venturis and 1.750" Throttle Blades.

The venturi size is 1.5625" minus 1.375" or .1875" larger (3/16").
The Throttle Blade size is 1.750" minus 1.6875" or only .0625" larger (1/16").

We know that the venturi size makes a difference in the carb total air flow. The Throttle Blade Size not so much because every double pumper carb from a 650 cfm carb to a 800 cfm carb used the same Throttle base/Throttle Blade size. The air flow difference was due to the venturi changes.

So here is the carb question for you:
If both carb are tested at the same test pressure for a 2-BBL, (40.8" of water) and the Venturi size and Throttle Blade size is quite different, How can they both be Holley 500 CFM Carbs?

The end carbs for the 6-pack set-up are obviously low rated for flow vs their actual flow rating. See my point now.

Chrysler/Holley was playing Carb advertising games with the insurance people and the Racing Organization People. Much lower rated CFM vs what the carbs would really flow on the engine.
You can't miss-advertise up but you can miss-advertise DOWN.

Tom V.

I am working on a Tri-Power Holley carb set-up that uses a 6-Pack End Carb Mainbody (Big Venturi) as the CENTER Carb of my Mechanical Linkage Barry Grant 6-Shooter Ported Intake set-up. Should work great on a 482 cid NA engine.