The Pontiac Tri-Power Story

LEAD TRI-POWERNothing looks more awesome under the hood of a classic Pontiac muscle car than the factory triple-carburetor system known as Tri-Power. Here’s the story behind the legendary setup. 



Offered on select models from 1957 through 1966, Pontiac’s Tri-Power induction system added a new dimension of performance to the General Motors brand—and a colorful new term to the hot rodder’s vocabulary. Tri-Power has an interesting background. Let’s jump right in.


1957 Tri-Power

The Pontiac Tri-Power story formally begins in December of 1956 with a General Motors press release announcing the setup’s availability on the 1957 Pontiac line (factory photo above). But we could say the ball actually started rolling back in 1955 when the Rochester 2G series two-barrel carburetor was introduced, which made the Tri-Power concept possible.

Founded in Rochester, New York in 1908 and acquired by General Motors in 1929, Rochester Products was originally a supplier of electrical components, from cigar lighters to starter motors. In 1950 the division diversified into carburetors, and the 2G series (2GC, 2GV, 2GE, etc.) first produced in 1955 was one of its most popular models, installed on tens of millions of GM cars through 1978. A simple, inexpensive, and virtually bullet-proof design, the Rochester two-barrel was—when used in multiples—inadvertently ideal for high-performance applications.

For the 1957 model year, Pontiac’s brand new general manager, Semon E. “Bunkie” Knudsen, had gone to work overhauling the division’s dated image and building more excitement into the product. “You can sell a young man’s car to an old man, but you can’t sell an old man’s car to an young man,” Bunkie famously said.

To that end, more horsepower was definitely part of Knudsen’s program, and for two years starting in 1957, Pontiac offered Rochester mechanical fuel injection with a system very similar to that used by Chevrolet. The fuelie setup was advanced and effective, but not without its problems, including reliability, serviceability, and cost—a whopping $500 per vehicle.


Tri-Power brochure page

For a low-cost alternative to the expensive fuel-injection system, Pontiac took a page from racers and hot rodders, who for years used standard, off-the shelf carburetors, simply adding more of them to provide more fuel volume and greater breathing. In American hot rodding, two and three-carburetor setups were the norm, so Pontiac engineers took the obvious step. A basic design with few components, the Rochester two-barrel had a dirt-cheap unit cost, perhaps $5 to $10 each. This allowed Pontiac to offer the three-carb Tri-Power system for only $90 to $100 per car (see brochure above). This was a fraction of the cost of the fuel-injection system, or alternately, a pair of fussy and expensive four-barrel carburetors from Carter or Holley, and still allowed for a healthy markup.

While the three-carburetor setup looked impressive and complicated, in fact it was fairly simple. Only the center carburetor worked on starting and at low speeds, providing reasonable driveability and fuel economy. But at larger throttle openings, the front and rear carburetors—which had no chokes or idle circuits, only main and accelerator pump circuits—opened progressively via a vacuum servo. The system functioned much like a typical four-barrel progressive carburetor, but with superior breathing thanks to six throttle bores rather than four.

With the Tri-Power induction setup, Pontiac was able to offer performance similar to the fuel-injection system but at a far more reasonable cost. In fact, Motor Trend magazine reported at the time that Tri-Power induction was slightly but measurably faster. And of course, nothing says high performance like a row of three carburetors under the hood. The Tri-Power legend was born.


1957 Olds J-2

The other GM divisions were quick to offer their own 3X2 Rochester induction systems, as Oldsmobile, Chevrolet, and Cadillac all offered their own variations on the theme. In January of 1957, Oldsmobile introduced the J-2 package (above) for the 371 CID V8, offering the option for two years. And in 1966, Olds returned with a similar 3X2 system for the 442.

While the Tri-Power name was a Pontiac exclusive, the term quickly gained what is known as the Kleenex effect, becoming a generic trademark. Car enthusiasts began to call all three-carburetor setups “Tri-Power,” regardless of origin. A new term entered  the gearhead’s vocabulary, much like the Chevrolet trade name Positraction, which you will hear applied to a limited-slip differential from any manufacturer. You can’t buy that kind of word-of-mouth publicity.


1958 Chevrolet 348 3x2Cadillac offered Rochester 3X2 induction from 1958 through 1960, replacing the expensive 2X4 Carter system used to that point. Chevrolet (shown here) used the three-carb setup to good effect on high-performance versions of its 348 CID V8 from 1958 to 1961. Note the choke thermostat on the center carburetor only, the bowl-type fuel filter, and the mechanical linkage connecting the front and rear carbs.


1965 Ram AirPontiac offered Tri-Power on select models and engines (347, 370, 389, and 421 CID) from 1957 through 1966, when it was finally superseded in 1967 by the Rochester Quadrajet four-barrel, a more modern air valve-type carburetor. On the Pontiac GTO (shown) equipped with manual transmission, the vacuum-operated throttle was replaced with a mechanical progressive linkage.

Also shown here: In 1965, Pontiac began to offer an fresh-air induction system, initially as an over-the-counter dealer package that sold for $30 and included a carburetor pan, a foam seal, and instructions for making the external hood scoop functional. While in truth, the scoop was too small and shallow to provide any significant increase in air pressure, Pontiac named the package “Ram Air,” and another familiar hot rodding term was born.


Pontiac Tri-Power right

10 thoughts on “The Pontiac Tri-Power Story

  1. Boom. Nailed it. The strongest selling point (beyond the kick in the pants) was the sound – “a Hoover-God sucking up sinners,” as David E. noted in a retrospective of GTO #1.

    Other fun facts: Ram Air was only available on the GTO, not on the larger B-Body Catalina/Bonneville.

    In ’66 only, the center carburetor was enlarged to match the end units, offering slightly improved breathing and low speed response. In ’66, the first of the Ram Air GTO’s were released with the rorty -744 camshaft and the tri-power, teamed with mandatory 3.9, 4.11 or 4.33 gears. Road tests of the day praised the dragstrip performance, but panned the street drivability and atrocious fuel economy, assuming anyone cared.

    To the point of the carbs cost, I’d be surprised to learn it would be more than a dollar or two. The unit savings produced by the massive leverage of GM capacity at full chat were unbeatable, even with usurous transfer prices from component divisions. The real cost would be the hand labor to assemble the carbs, fittings and linkage to the manifold. There are a lot of pieces to that kit.

  2. How many CFM are those carbs? About 200 I feel. The old Stromberg 97s are about 150!
    These are obviously a good period piece but way out of date. I am not surprised that the Q Jet made all of this obsolete

    • The ratings are suspect… Need constant temp, pressure drop and humidity. One of the 2GC rochesters is about 250, total of about 750 @wot. There wasn’t a street 4-BBL before Q-Jet that could approach the air volume. As noted elsewhere, the more an amateur messed with it, or God forbid, took all three apart, the worse it ran. $50 would get you stacks of tripowers that were abandoned under workbenches and basements bak when. You couldn’t buy an NOS fitting for that today.

  3. I worked in a Pontiac shop in ’67-’68. The biggest problem with the Tri-Power setup was the car’s owner. About 70% of the owners would try to “improve” the Tri-Power setup, totaly hose the setup and carbs, then wanted us to fix it under warranty.
    But when they were right, it was an awesome setup.

  4. In the early sixties, my car-hating father somehow ended with an ultra-flashy ’59 Bonneville hardtop equipped with a Tri-Power 389. As a car crazed six year old, I was impressed with the jet-like performance but all my dad did was complain about the necessity of premium fuel and the horrible mileage. Despite my pipe dreams of it being stashed away until I was old enough to drive, it was traded just a few years later on a sensible (read totally boring) Plymouth Fury sedan.

  5. Had a 1960 Chiefton with mechanical linkage. The deep tone was very pleasant when the secondaries opened but it got almost 6 mpg doing that.

  6. How about the “fussy and expensive four barrel carburetors from Carter or Holley” in comparison with GM’s own Rochester 4GC?

    • The Rochester 4GC was totally unsuited for multiple setups, due to its fuel inlet location among other things.

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