Pontiac Trans Am SD-455: Did Pontiac Save its Best Muscle Car for Last?
It was over, Johnny. The muscle car thing had run its fun, psychedelic course by the early 1970s. Rising insurance rates, falling compression ratios, and looming federal regulations effectively killed the fun like your junior high principal turning on the gymnasium lights at the end of the eighth-grade dance. Time to go.
Pontiac lingered as long as possible, and the Super Duty 455 engine was the final song they got the DJ to play as everyone shuffled off the floor.
That the SD-455 was produced at all was a miracle, given how quickly high-performance became politically incorrect by the early 1970s. Installing it in the Firebird was another challenge because the F-Body line was very nearly canceled after 1972. Sales for ponycars dropped precipitously as younger buyers sought more fuel-efficient cars. Consequently, Firebird sales plunged more than 56 percent between 1971 and 1972, to less than 30,000. Only 1,286 of them were Trans Ams.
Fortunately Pontiac was filled with passionate people, and they pushed the Super Duty 455 project along. It helped that the engineers were deep into the project when the market turned against high-performance cars, so it seemingly wouldn’t take much to push the SD-455 over the line.
Pontiac introduced the engine to the press in the summer of 1972, during the brand’s annual model line preview. Unsurprisingly, the response was enthusiastic. There was much to be excited about.
Almost every element of the engine was unique, from the block and heads to the rotating assembly, intake manifold, carb, and more. It was announced at the introduction with a 310hp rating, along with plans to make it available at the start of the 1973 model year. That didn’t happen. Creative interpretation on Pontiac’s part of EPA’s emissions test for certification didn’t go as planned, which pushed back production.
By the time Pontiac recertified the engine, with a revised camshaft and commensurate carburetor adjustments, the horsepower rating was revised down to 290. It was the spring of 1973, but the cars didn’t roll off the line in meaningful numbers, creating a significant customer relations problem. The company had stacks of preorders for cars it couldn’t deliver. By the end of 1973 only 295 Super Duty-powered Firebird models had been built: 252 Trans Ams and 43 Formulas.
The engine added $521 to the bottom line for a Trans Am and $675 for a Formula. A four-speed manual transmission was standard, and the stout Turbo 400 three-speed automatic was optional. Air conditioning was available with the automatic transmission, but that pushed the rear axle ratio up to 3.08. Non-A/C cars received a shorter 3.42 gearset.
There was plenty of confusion about the horsepower rating. Before the Internet the only reference data most enthusiasts had were six-month-old magazines promising 310 horses. Nevertheless, when the SD-455 finally hit the street, praise for it was universal, especially when it turned mid- and high-13-second e.t.’s at a time when a new big-block Corvette generally required another full second to run the quarter-mile.
It was great performance indeed for a 3,800-pound Firebird with smog equipment and a compression ratio of only 8.4:1, but the 395 lb-ft of torque and the exceptional airflow of the special cylinder heads more than offset the mandated handicaps. Even down a few horsepower, thanks to a “smaller” camshaft than the original spec, the production model was the quickest car out of Detroit in years.
The end for the SD-455 came too quickly for enthusiasts. With catalytic converters on the docket for 1975 and other related emissions changes, Pontiac knew from the very start the engine wouldn’t live beyond 1974, but it was a hell of a ride while it lasted.
Ironically, the enthusiasm for the engine wasn’t matched by sales. The delayed release in 1973 certainly squeezed the production run in the first year, but only 1,001 additional SD-powered cars were built in 1974, bringing the two-year total to 1,296. Cost was a likely factor, as the $521 premium for the Trans Am was the equivalent of more than a $3,700 option in today’s money, adjusted for inflation. And that was actually a premium on the already extra-cost 250hp 455 engine, which made the true cost more like $700 over a base Trans Am model. Some dealers also charged more because of the car’s scarcity. Bottom line: 13-second e.t.’s from the factory didn’t come cheap.
Collector John Nikolas was too young to drive when the Super Duty 455 finally hit the street, but his neighbor drove a 1974 Buccaneer Red example as a company car. His company happened to be General Motors and the neighbor happened to be Pontiac general manager Martin J. Caserio.
“I always admired the cars he’d bring home, including early Firebird Formulas that would chirp Second gear going up his winding driveway,” says Nikolas. “But it was that red Super Duty car that really stuck with me. I knew I had to have one someday.”
Today Nikolas owns four SD-455 Trans Ams, a white 1973 model and three from 1974, including the Cameo White example profiled here. A 51,000-mile car he purchased in 2004, it was sold originally in Texas and filtered through a few owners, including a well-known collector in the SD-455 world who owned 19 of them at one time, before ending up in a quiet area of western Michigan.
“The car was listed online for a long time, but it was located kind of far away from everywhere,” says Nikolas. “I was apparently the only one who drove all the way out there to check it out in person and bought it on the spot.”
The previous owners all took excellent care of the car. It was never modified, and every original component that was replaced over the years for maintenance or repair was never thrown away. Nikolas has them all in a box.
It’s a very well-equipped Trans Am, too, with the Custom interior that included a specific “horse collar” seat upholstery design with detailed piping, specific door panel trim, and a grab handle on the dashboard. The car also features power windows, power locks, air conditioning, and more, a collection of options that helped push the sticker price to nearly $6,300. That slower 1974 big-block Corvette cost about the same.
Nikolas purchased the car with the intent of a concours restoration, which he’d recently completed on his 1973 Trans Am, but the plan changed as he continued to enjoy the remarkably unmolested car.
“It’s a great driver with a lot of torque on tap,” he says. “Just jump in and go. I drive it to work regularly and take it cruising on Woodward Avenue in the summer. I’ve driven it on a couple of the Hot Rod Power Tours. It has never let me down.”
Although it hasn’t been restored, it was repainted sometime in the late 1970s, which was all too common for cars of the era, especially in climates such as Texas where the sun is unrelentingly punishing on thin factory paint jobs. It also has a new headliner and some light upholstery work accomplished with N.O.S. material that came with the car.
One more thing: The iconic shaker scoop has been opened up to feed fresh air into the Quadrajet carburetor. When introduced in 1970, the shaker was a functional fresh-air inlet, but Pontiac capped it off in 1973 for noise reduction. Perhaps anticipating owners’ actions, the scoop was sealed with a simple plate held in place with only a trio of easily defeated rivets.
“Between the performance and the mystique surrounding the engine, there’s really something magical about these cars,” says Nikolas. “They not only represent the last of the true muscle cars, but the sort of confident, no-holds-barred engineering that really made Detroit great.”
At a Glance
1974 Trans AM SD-455
Owned by: John Nikolas
Restored by: Unrestored (1970s repaint)
Engine: 455ci/290hp LS2-code Super Duty 455
Transmission: Turbo 400 automatic
Rearend: 10-bolt with 3.08 gears
Interior: Custom “horse collar” vinyl bucket seats
Wheels: 15×7 Honeycomb
Tires: 225/70R15 BFGoodrich Radial TA
Special parts: One of only 943 SD-455 Trans Am models built in 1974
The rear of the 1974 Firebird lineup was updated with a new bumper that stood up to federal 2.5-mph guidelines. Wider, body-color taillamp surrounds were also part of the model-year upgrades.
The Super Duty 455 was originally spec’d with a high-lift camshaft that helped it produce 310 hp, but the bumpstick was changed to satisfy EPA emissions certification, pushing output down to 290 horses but with a strong 395 lb-ft of torque.
The SD-455’s carburetor was the familiar spread-bore Rochester 4MV Quadrajet but rated at 800 cfm. It was similar to other 750-cfm versions used on Pontiac engines such as the 455 H.O. but used larger primary venturis.
Super Duty engines were unique in having the PCV blow-by tube exit through the oil filler cap rather than the conventional valley location.
Inside, the Trans Am was essentially unchanged for 1974 but offered more color and trim options. Curiously, the sport steering wheel that was standard with the Trans Am was called the Formula wheel. It was only optional on Formula models.
The Rally gauge cluster that included a tachometer and clock was standard on the Trans Am and optional on the Formula. The engine-turned dash applique was exclusive to the T/A.
Optional honeycomb 15-inch wheels looked like cast aluminum, but the wheel center was actually an injection-molded composite piece bonded to a steel rim.
The famous large hood bird graphic (RPO code WW7), also known as the Screaming Chicken, debuted on the Trans Am in 1973 as a $53 option. The blue color of the bird here was offered on cars with white or blue exterior colors.