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Holley 3150 and 3160
This three barrel model was brought out in the early 1960s to provide higher flow capacity for NASCAR racing engines. Later they were applied to drag racing and saw some street applications.
Increased capacity was obtained by making the primary side as large as possible with 1 9/16 inch venturi and 1 3/4 inch bores. Material between the secondary venturi and bores was removed, resulting in oval shaped sections of 1 9/16 x 3 7/16 inches in the venturi and 1 3/4 x 3 5/8 inches in the bore.
The oval secondary is diaphragm operated, but because velocity and signals are low due to the large size, a special diaphragm assembly was designed. The manual choke is spring loaded open. The air horn is cut away.
Because these carburetors were so large, secondary opening characteristics were critical. Remember, just because the secondary plate is open doesn’t necessarily mean that the nozzles are feeding. Venturi velocity must be great enough to provide an adequate metering signal. Calibration is a little tricky, but some people used them with great success, especially with large engine., high RPM applications.
Carburetor size limitations for the small block engines and the introduction of the model 4500 Dominator Carburetor for big block engines signaled the end of the 3160 use in NASCAR. Likewise, the model 4500 became the more popular way to go in drag racing classes that permit unlimited carburetor size. Two 3160 models of 950 CFM and 1050 CFM were offered for quite a few years, but finally dropped in 1974. The added capacity of the 0-4604 was obtained with very small booster venturi.
If you have one of these carburetors, hang on to it, you have a collector’s item.
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