750cfm – 55% more than regular 97s

Stromberg Carburetor worked closely with Norm Schenk at Competition Fuel Systems, Tucson AZ, to provide more airflow than regular 97s without changing the classic 97 shape. Independent tests have rated BIG97s at 250cfm per carburetor. That’s 55% more than our own regular 97s (162cfm). Here’s how we did it:

BIG97s move up to a 1.175in venturi with super-efficient 20 degree entry angles encouraging maximum pressure drop into the venturi, with minimum flow loss and excellent signal stability.
Bigger, thinner 1.34in throttle plates work within offset throttle bores, while flared exit cones ensure good pressure recovery and low turbulence in the mixture leaving the carburetor.
BIG97 accelerator pump discharge jets (Primary carburetors only) are smaller and located higher up, well out of the booster airflow.

A new, oval ‘early plenum’ shape, just under the throttle plates, helps the two separate barrels of air come together before they hit the intake plenum. This improves pressure recovery and increases airflow capability, but also builds power by slowing the mixture down to reduce turbulence in the transition from carburetor to manifold plenum.
Coupled with our recommended intake manifold modifications, connecting the two manifold planes has further benefits as allowing any cylinder to draw from all six barrels brings the strong torque and easy drivability of a dual plane intake with a boost in top end horsepower more usually associated with a single plane.