How to Rebuild and Modify Rochester Quadrajet Carburetors
Secondary Accelerator System
In the caption "Ready for Assembly," I discussed the slotted air valves pictured along with the rest of the carburetor. Those slots were designed to expose the secondary accelerator system openings to the intake when the throttle is opened far enough to actuate the secondaries. When I wrote that having those openings below the air valves was the "most useful," I was referring to the arrangement of a few carburetors machined like the one pictured, above. As Cliff Ruggles explains in How to Rebuild and Modify Rochester Quadrajet Carburetors, what this arrangement does is improve throttle response when getting on the throttle hard enough to open the secondaries. It quells hesitation by removing the momentary impediment created by the air valves before they respond to the engine air requirements and tip open far enough to allow a straight path for the fuel from those orifices into the engine. In fact, Chapter 6 provides a couple of options for solving this dilemma on standard Quadrajets, but I'll let you read the book to find out what those are. Photo: Cliff Ruggles.
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