Carter Carburetors ~ Advertised CFM Ratings and Corrected CFM Flow Ratings ~

Rusty-Rat-Rod

A Very Good Question

Most of Carter Carburetors 'CFM-Ratings' were based upon generalized 'advertised'
guestimates.

Calculations were based upon Throttle-Bores sizes and Venturi openings.

1} Unfortunately, Air-Flow is 'not' Air-Flow.
2} Street Engines operate below maximum capacity.

The ratio of how much air the engine can pump is called, as you know
VE {volumetric efficiency}.

As a general estimate, the following Engines operate at;
Street Engines .......... 75%
Modified Engines ....... 85%
Race Engines ............ 90%

~ Advertised Ratings ~

Most calculations performed at Carter for the AFB used 75% as a guestimate.

The AVS was rated at approximately 85%, as it was designated as a Performance upgrade.

The Thermoquad was rated at the high-level of 90%.
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~ General Carter Carburetor Formula {High CFM Flow Rate}

Throttle Bore {multiply by} Venturi {multiply by} .743 = Bore CFM