Live Auctions

Is It Real? 1974 Pontiac Trans Am Super Duty

“We Build Excitement” was the catchphrase for Pontiac, and that was certainly true when the 455 cu. in. Super Duty engine arrived on the scene in 1973. Against all odds – given the anti-horsepower climate at the time – the last muscle car engine of an era made it into some 1,296 Trans Am and Formula cars. These cars command premium prices in the marketplace today and will likely continue to appreciate thanks to rarity, performance, and historical interest. Finding one of these rare cars is an electrifying experience. Perhaps here in Hemmings, where a 1974 Pontiac Trans Am Super Duty is for sale for $31,000 firm, that thrill can play out for a new owner. This car is located in Hampton, Virginia. We have PRA4SNW to thank for this fascinating tip.

This car is advertised as a one-owner daily driver with 108,350 miles. By January of this year, the owner could no longer drive, thus the sale. The seller claims that the car has “original equipment” but then notes the installation of aftermarket upgrades such as an MSD ignition system, exhaust and intake manifolds, carburetor, and valve covers. Unfortunately, all these changes detract from the value of this car, and judging by the price at half or less of a fully equipped SD Trans Am, my guess is those original items are long gone. Meanwhile, despite the seller’s indication of “numbers matching”, there’s a lot of work to do to verify the engine. The 455 SD was a specially cast, specially built, specially equipped beast with a romantic genesis catalyzed by passionate employees. While Pontiac installed a 455 cu. in. motor in plenty of cars, if it wasn’t a Super Duty, it wasn’t unique and it doesn’t deserve a premium price. Nor can a regular 455 be “built” into an SD. Extra bracing cast into the lifter valley and a casting provision for a dry sump oil system at the rear of the block are just two of many idiosyncracies that make these engines iconic. The 455 SD produced 290 bhp, while the ordinary 455 came in at 250 bhp. This car does have the right VIN indicating a Super Duty build (the “X” in the VIN is what you want to see), and the transmission is a four-speed, which is desirable. But we already know it doesn’t have the original Rochester carburetor, manifolds, and valve covers installed – demerits for sure. That shaker scoop was an actual air intake until 1973 when Pontiac capped it off with a metal plate held by three rivets, to reduce noise. Many owners have opened up those scoops (“cut”) and some have not (“uncut”).

The interior is in good condition – better than either the engine bay or the exterior. The seller does indicate that the car has received a recent appraisal, but doesn’t provide any details. In fact, the ad has only five photos, and two of them are of the interior. If I had a Super Duty, I would probably post as many engine photos as I could.

This car offers a compromise for the collector aspiring to a Super Duty: a price roughly half or less of a verified, truly originally equipped SD, but with the cache of a potentially real SD block, that manual transmission, and one-owner history. What do you think: is it worth it?


  1. alphasud Member

    The sellers addition of the performance items is what makes this a super duty in the sellers eyes. It might be a numbers matching car as a regular 455 4-speed which is still a very big plus. The buyer will need to do some sleuthing to find the answers. Thanks Michelle for pointing out how special the SD engines are. I have tried to understand the intricacies of these engines hopefully someday it will all come together between the 421, 428, and 455 high performance variants.

    Like 6
    • Nick P

      Apparently, the car has the “x” in the vin. That is what makes it a super duty in everyone’s eyes.

      Like 1
  2. Sfm5

    I would think a nearly 50 year old car that has been a daily driver would have more than 108K miles on it? That’s only just over 2K miles per year – for a daily driver? Not really buying it.

    Like 5
    • Steve-O

      It was probably their daily driver for the first ten years or so then parked. They should be a little more specific. I can’t see someone using this as a commuter in the last thirty years.

      Like 10
      • NoFear

        The SD T/A I purchased last year was used as a commuter car for a while when the owner drove it from Oregon to Virginia. It still has the commuter stickers on the bumper and the parking sticker for a Naval installation in VA.
        But agree that was a long time ago and mine hadn’t been used as a commuter for many, many years.

        Like 2
  3. Motorcityman

    290hp 🤣🤣!
    If it’s a REAL SD 455 it’s really a lot more!!
    These cars in real good shape are worth about 100K so this one at 30K or so isn’t a bad price….IF it’s a real SD.

    Like 2
  4. Steve B

    My bet is that it’s not an SD. 5th digit of the VIN is likely a “T” or a “Y”, indicating 400 or standard 455.

    Like 1
    • Roland Schoenke

      Writer already stated the x in the Vin.

      Like 5
  5. Tom

    If it is an original SD, which this article claims it is, the missing carb, intake and exhaust manifolds is a big deal! Good luck finding correct replacements! Hopefully someone has the correct parts and will save this one

    Like 4
  6. Johnny

    Nice to read and see comments about this car. I know where one is. Its a 455,but not sure which motor. Its a one own and has all the original parts. Been parked along time and was offered to me awhile back. Gotta get back in touch with him.

    Like 5
    • Motorcityman

      Totally different engines.
      The SD is literally a race motor and only made in the TA in 73 and 74.

      Like 3
  7. Homer

    I worked for a Pontiac dealer from 72-82 and every time I see one of these it reminds me of all the Asians who bought the car because of Smokey and the Bandit. Many found their way to the body shop shortly thereafter.

    Like 4
  8. Harry V. Quackenboss

    There is a comprehensive two-part series titled The Pioneers of the Pontiac V8, originally written for High Performance Pontiac magazine, now available via a web search on the website. I would encourage Pontiac aficionados to make their own copy, because stuff disappears from the Internet.

    The brain trust behind the SD-455 included Herb Adams, Tom Nell, and Jeff Young. In a recent conversation with Herb Adams, he told me that with the original proposed production configuration, the camshaft had enough overlap that it actually didn’t need an EGR system to pass emissions. His observation was that the other production engineering people who took over the SD-455 to finalize the production configuration, in addition to cutting costs, such as using an iron intake manifold, lowered the performance by changing the camshaft to one, which did require EGR.

    My understanding, from Herb Adams is that Tom Nell had used his informal connections in the engine manufacturing organization to get them to order parts to build engines before the program was approved for production. By the time that decision was made, John DeLorean, who was a strong supporter of Herb, had moved on, and the successor general manager had a different perspective on pretty much everybody that DeLorean supported. The new general manager was put into a situation where either they built production motors, or the engine plant would have to write off the inventory. I wasn’t there but my surmise was that would probably hurt the general manager’s bonus, which outweighed his distaste for the unofficial racing and performance program that had helped make Pontiac successful.

    Prior to the SD-455 in the 1970-71 time frame, they engineered a special strengthened cylinder block for NASCAR 6-liter (366 CID) and produced about 50 blocks that included the dry sump pump provision. They were, in 5 Liter (303 CID) motors: (1) the 1964 Pontiac Tempest built by a team of Pontiac engineers that was raced by Bob Tullius in the Trans-Am series in 1971, and then SCCA A Sedan by Louie Spoerl, who purchased the car at the end of 1971, (2) Pontiac Trans Ams raced in the NASCAR Grand American series owned by H.B. Bailey (these were also 303 CID), (3) the 1972 Firebird driven to 2nd in the Trans-Am series by Milt Minter, and (4) the NASCAR Cup 1973 Pontiac Grand Am, built by the Pontiac engineers, and raced at Riverside, CA in 1973 driven by Jerry Thompson, who ran as high as 7th, and then failed to make the race at the Daytona 500.

    Key people on those engines, and the SD-455 were Herb Adams, Tom Nell, and Jeff Young, Tom Nell had a moonlighting business run out of his home building Turbo 400 transmissions for drag racers, and I believe, deserves credit for teaching B&M what he knew. In the race motors and the SD-455, using the automatic transmission pump for the dry sump pressure side, driven off the back of the camshaft was Tom’s invention, with a production in the pan pump for the suction side.

    Jeff Young had graduated from MIT with a master’s degree and came back to apply what at the time were very advanced airflow principles to the Ram IV heads used on the 366 and 303 race engines described above, and the SD-455 heads. The SD-455 heads have larger ports, and include a tube for the pushrod in the port. According to Herb, they never could get the Ram V heads to work, although various engine builders have claimed in larger displacements, and running higher RPM than the 7500-7800 RPM that were as high as they would reliably run in the 1970s, the Ram V heads can produce good power.

    An anecdote from 1971 illustrates the competitiveness of those race engines that preceded the SD-455. At Watkins Glen in 1971, we had problems with detonation, attributed to sub-par fuel purchased at the track, and ran the race on a motor assembled from two broken ones. An exhaust port burned through to the water passage, forcing frequent stops for water. But after the race I introduced myself to a guy in the paddock with a radar gun slung over his shoulder, who had recorded speeds for all the cars. I didn’t write them down, but from memory, the Penske/Donahue Javelin was at 154/155, several Camaros were at 155/156, the Bud Moore Mustangs were at 159, and the Tempest was at 157. Corroborating this was the qualifying performance of the H.B. Bailey Firebirds at the February, 1972 NASCAR Grand American season opener on the road course, but this was prior to the introduction of the bus stop chicane, where H.B. Bailey qualified 2nd behind, I think, a Ford Mustang, and Herb, never having been at the track, qualified 4th.

    I wasn’t a GM engineer, but I goffered on the Gray Ghost Tempest, and was the suspension/brakes lead on the 1972 Firebird and the 1973 NASCAR Cup Grand Am and worked on H.B. Bailey’s Grand Am Firebirds.

    For as much publicity as Herb Adams has received, he was always the first to give credit to the team members.

    Like 30
    • 19sixty5 Member

      Great reading Harry! I appreciate some more of the background.

      Like 5
  9. S

    I think it’s awesome Pontiac offered the Super Duty 455 right when emissions, the fuel crisis, and insurance companies were conspiring to prevent cars like this from being built. That’s the kind of thing that makes Pontiac a legendary brand. I don’t know how many 74 Trans Ams were built in total, regardless of whether they had the Super Duty engine – but it doesn’t seem to be a popular year. You never hear about a “74” Trans Am of any kind. I love the interior on this – nice seats, even nicer in white. No matter what the story is with this car, it’s an awesome find. Also awesome that it’s the original owner, so the entire history of what has been done to the car can be determined. Few people keep a car for 48 years – so the owner obviously cared enough about the car to do that.

    Like 3
    • Motorcityman

      Just under 10,000 Trans Ams built in 74 according to my Firebird “Red Book” but only 943 SD 455s

      Like 2
  10. 19sixty5 Member

    Not the best ad ever posted for sure, a bit light on the description and only a handful of photographs of such a rare car make you scratch your head. A PHS report would show if this indeed was an SD car, but detailed photographs of the engine showing the stampings on the block, casting numbers and dates, etc. I’m sure there are SD cars running around with a standard 455 in them. But… a reasonable price for such a rare car.

    Like 1
    • Nick P

      Don’t need PHS to verify being a real SD. X in the vin means SD

  11. jwzg
  12. Emel

    For the size engine….. these cars were really dogs. Never lost one !

    • Motorcityman

      455 is NOT the same car as a SD 455

      Like 2
      • jwzg

        The SD was also very conservatively tuned. A distributor recurve and thinner metering rods were all that was needed to put down around 300 hp to the wheels which translated into well over 400 gross hp…still comparable with anything built in or before 1970. A camshaft, bigger carb and Ram Air IV would put this over 500 hp.

        Like 6
      • jwzg

        Ram Air IV exhaust manifolds…

        Like 2
  13. George Mattar

    A correct Quadrajet for a true SD will set you back $4,000. The market for these isn’t as large as many think. I follow numerous auctions and have owned numerous muscle cars. I also a former editor at Hemmings, where this car is advertised. Personally, I want a 1973 SD in Brewster Green. One year only color. Pontiac did plenty behind the scenes to bring this engine to market, but got caught messing with the EGR valve.

    Like 1
  14. Motorcityman

    I’ve owned over 100 cars and drove a friend’s BucaneercRed SD 455 TA……that 290hp rating is a Joke!
    I KNOW what 300hp feels like! The SD had at LEAST 400hp!!

    Like 7
  15. Richard Main

    Ok. In 1972 I bought a T/A white, blue stripes, 455 HO from Mickey Thompson in Palm Springs. I then had Nunzio redo the heads to SD configuration, changed to a Holley 750 double pumper and a few other upgrades. Ran it with a 2.73 rear axle street tires, did 60 in first gear at 5750, max piston speed as I recall. Ran it at old Carlsbad, California 1/4 mile and did 12.7 @ 112 MPH. Trust me (I have two T/A’s highly modified now, I am 84) and I can guarantee the engine put out north of 500, as did the L-88 in my boat.

    Like 3
    • Motorcityman

      Do u know that Pontiac engine builder that has a shop in Grand Terrace Ca.CA.? It’s on Michigan Ave. I believe…..not sure if he’s still there, this was around 1997 or so.

  16. Troy s

    Lots of good history written here today,, on the final “outcast” Pontiac, first being the GTO. Never owned a SD 455 ‘bird but from everything I’ve learned about them over the years they ran really strong. I’ve possibly seen two of these, once at Carlsbad Raceway but it was hopped up pribably had a bottle , and one at a car show. To be honest, I’d rather have a Formula with the 455 SD, but the Trans Am would be just fine and dandy. Blue with white stripes though.

    Like 1
  17. 455RAIV

    Good deal for a real SD-455 T/A – For a Bit of History on the SD-455 Engine – The PMD Test Mule SD-455 12.5 – 1 Compression HL RA IV Cam etc. Dynod @ 600 hp before it was detuned for production – they said you could hear it run all over the Large Pontiac plant no matter were you where :)

    Like 2
  18. Des Member

    Looks like it didn’t last long.

    • Motorcityman

      There’s a white 78 that looks pretty good for 24K

  19. PRA4SNW PRA4SNW Member

    This listing was completely removed from Hemmings, leading me to believe that it was not real to begin with. They have one other SD-455 listed with no price, so I looked it up on the seller’s website. It is going for 98K. It’s of course in a lot better condition, but that is a price a price I would expenct to see for a Super Duty.

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