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Carburetor Classics: The Racy Rochesters

A mainstay of GM vehicles

Rochester Products Division (RPD) of General Motors has built millions of carburetors over the years, but only a few have been popular with high-performance fans. The 2G series (in 3X2 setups), the famed Quadrajet four-barrel, and the pioneering 1957-1965 Corvette Ram-Jet fuel injection setup have loyal followings that are still rabid about Rochesters.

2G Series

The 2G series of two-barrel carburetors was introduced in 1955. Although intended for use on bog-slow grocery-getters, hot rodders quickly discovered it was more advanced than the obsolete Stromberg 97. Of course, just one was not enough, yet triple 2Gs were soon showing up on hot rod manifolds. In 1957 three 2Gs were mounted on the Oldsmobile J2 performance engine, and the next year the 348 Chevy was similarly treated. In 1964, triple Rochesters graced the legendary Pontiac GTO, and later some Olds 442s breathed through triple 2Gs as well.

The center carburetor had all normal carb functions, while the outer two carbs did not have chokes. Factory triple carb setups had end carbs with vacuum operation, while hot rodders preferred a mechanical linkage.

The Rochester 2G series was sold in a wide variety of sizes and configurations. The largest are still prized for use in certain circle-track racing classes where a single two-barrel carburetor is required. Although the 2G has been out of production for some time, used units are still being rebuilt and modified for racing. There are also multiple-carb manifolds still available to install Rochesters on Buick and Chevy engines for the retro-rod and vintage racing markets.

Quadrajet

In 1965, RPD introduced the Quadrajet four-barrel carb that could be made in a wide variety of sizes to fit large and small V-8 engines. It had many advantages, including excellent fuel control due to its centrally located float, which was highly resistant to level changes caused by cornering or acceleration. It was also relatively easy to modify and quickly became popular with off-road, circle-track and road-racing teams running V-8 powerplants. Among the many classic musclecars wearing Q-Jets were the LS5 454-inch Corvette, SS396 Malibu, Olds W30 4-4-2, Pontiac Firebird 400 and the GTO "Judge." Due to their excellent street manners, Q-Jets were also used on many standard-equipment Corvettes and other General Motors sporty cars.

In the 1970s, Quadrajets held many drag race records in the stock classes, and Corvettes powered by Q-Jet-equipped 350s drove the 289 Cobras out of the SCCA B-Production class. Vic Hickey won many off-road events in Q-Jet-equipped racers.

The Quadrajet is still available in sizes up to 800 cfm. Although not as versatile as the famed Holley carburetors, the Q-Jet is appreciated for its tractable street manners and low maintenance.

Ram-Jet Fuel Injection

In 1957, Rochester got a jump on the future by introducing the first successful fuel-injection system in America. The Rochester Ram-Jet FI system (nicknamed the "fuely" system) was optional on Corvettes and full-size Chevys, while a similar system was available on some Pontiacs. However, the "fuely" Corvette became the most famous car to carry the Ram-Jet unit.

By modern fuel injection standards, the Rochester is pretty primitive. It is an all-mechanical unit that has a constant supply of fuel and air waiting in the manifold for the valves to open. An air-metering unit calibrates how much air is entering the intake manifold, then controls the amount of fuel that is sent to the engine. The fuel and air are mixed in a tall, thin aluminum intake manifold nicknamed the "dog house."

The first intake manifolds had ribbed tops, but later some injectors had smooth tops. Although there were many models and improvements from 1957 to 1962, the units worked basically the same. This fuel injection system was designed by a team led by legendary Corvette engineer Zora Arkus Duntov. Armed with fuel injection and the first Chevy 4-speed transmission, the 1957 Corvettes blew the Mercedes 300SLs and Jaguar XK-140s out of victory circles at road races across America.

In 1963, the first-generation Corvette was replaced with the phenomenal Sting Ray, and Rochester upgraded its fuel injection system as well. Although the basic operation remained the same, the "dog house" was larger, more box-shaped and had a removable lid. It had more air volume, which allowed the 327 engine to produce an impressive 375 hp. However, with the introduction of big-block engines in 1965, the market for an expensive, more sophisticated 327 engine was shrinking. Plus, the Ram-Jet system was difficult to service and few mechanics had the experience or tools to properly adjust it. As a result, the Rochester FI developed a reputation for being unreliable and difficult to modify. It was dropped after the 1965 model year.

The once-despised Rochester FI is now recognized as a classic design, and original "fuely" cars now command vastly higher prices than carbureted examples (injected 1957 Vettes can top $100,000). Rochester was way ahead of the fuel injection revolution that took the American automobile industry by storm in the 1980s. And today, Rochester carburetors and fuel injection systems still have a strong cadre of fans that prize their 2Gs, Q-Jets and Ram-Jets as classics.