Edelbrock - Square Bore

This carburetor is very similar to the Carter AFB from the 60’s. It has a square bore flange like most Holley’s. The secondary throttle blades are mechanically operated and don’t start to open until the primary throttle blades have opened about 65%. Airflow through the secondaries is controlled by a weighted flapper-type air door called the auxiliary air valve, which prevents the carb from bogging down when the accelerator is floored at low speed. As air velocity through the carb increases, the valve is pulled open, allowing the secondaries to operate fully. Similar result to a vacuum secondary, but achieved using a different method. Float levels are factory set, although the fuel pressure must be correct. Changing jets, can be achieved without the need to drain the fuel from the unit. Like Holley, an installation DVD comes with a recently manufacted carbs. The Thunder series of carbs is fitted with an adjustable valve secondary which allows for simple & accurate tuning across the rpm range.

The Thunder AVS series of carbs is fitted with an adjustable valve secondary which allows for simple & accurate tuning across the rpm range.