In part one of our Carb Rescue story (Super Chevy July 2012) we showed how even a grungy, oxidized Holley Double Pumper carb that had been sitting inactive for decades could be brought back to as-new condition by the Holley Custom Shop. Tech Greg House stripped our old carb down, cleaned it up, replated the main body, bowls, and base plate, then reassembled the air/fuel mixer with all new parts.
This time around Greg will be handling the second most common and popular carb for classic Chevys, the Quadrajet. Rochester first came out with the Q-jet in 1965, as a replacement for the Carter four-barrel carbs previously used by Chevrolet. Unlike the standard "square bore" carbs before it, the Q-jet used a "spread bore" design, where the secondaries were much larger than the primaries, offering performance and economy advantages for base and performance factory engines. The Q-jet would remain GM's go-to carb until the late '80s, when fuel injection in various forms retired the carburetor from O.E. use.
For the street, the Q-jet is a great carb, offering cruising economy with its smaller primaries, but instant performance when the large secondaries kick in. Though they can be more difficult to tune than a typical Holley because of the extra internal parts and design, in the right hands a well tuned Q-jet is a solid performer. Follow along as we get our Quadrajet back into fighting trim.