Pontiac Never Offered a 455 in the 1970 Trans Am — So Why Do So Many Restored Survivors Have One?

The 1970 Trans Am’s engine lineup stopped at 400 cubic inches — the 455 wouldn’t arrive for another year. Here’s how that one-year gap still trips up collectors restoring survivors today.

Pontiac never built a 1970 Trans Am with a 455 under the hood. Not one. The big-block that collectors now associate with the car’s reputation as a corner-carving bruiser didn’t exist yet — Pontiac’s engineers were still a full year away from shoehorning it in. Yet drive around any cruise night or scroll through enough classic-car listings and you’ll eventually hear someone swear their “numbers-matching” 1970 Trans Am is running factory 455 power. The explanation isn’t a conspiracy. It’s a restoration shortcut that’s been quietly repeated for decades, and it says as much about how these cars actually left the factory as it does about how they’ve been patched together since.

About the video: Raiti’s Rides spends this walk-around with a 1970 Pontiac Trans Am finished in the car’s signature white-with-blue-stripes livery, running through why the second-generation Trans Am still holds up as one of the best-driving muscle cars Detroit ever built. The host leans hard into the car’s reputation for being more than a straight-line bruiser — a point plenty of viewers echoed in the comments, several of whom pushed back on exactly which engine was actually under the hood of a genuine 1970 car.

That back-and-forth in the comments turns out to be the real story. Several longtime Trans Am owners pointed out that the 455 cubic-inch big-block featured in the video’s description didn’t exist in the Trans Am lineup until 1971. The 1970 model came with exactly two engine choices, and neither one was a 455.

⚑ Featured Gear

Start Car Conversations →

As an Amazon Associate I earn from qualifying purchases.

The Engine Pontiac Actually Sold in 1970

When the second-generation Trans Am finally reached dealers in early 1970 — delayed months behind its planned introduction because of tooling and engineering problems — buyers had two choices, both built around the 400 cubic-inch block. The standard engine was the L74 Ram Air III, officially rated at 335 horsepower. Stepping up got you the L67 Ram Air IV, Pontiac’s most aggressive factory tune of the era, rated at 370 horsepower on paper, though it’s widely accepted among Pontiac people that the real number ran well past 400 once a car was actually on a dyno.

The Ram Air IV was also Trans Am-exclusive that year — you couldn’t order it on a base Firebird or Formula, no matter how much money you waved at your dealer. But it was brutally rare even within the Trans Am’s own production run. Of the 3,196 Trans Ams Pontiac built for 1970 out of 48,739 total Firebirds, only about 88 left the factory with the Ram Air IV. The other 3,108 got the Ram Air III. A 455 simply wasn’t on the order form, for anyone, at any price.

Why the 455 Didn’t Show Up Until a Year Later

The 455 HO finally arrived for 1971, and the way Pontiac got there is its own small engineering story. The Ram Air IV’s round-port heads — the same castings that made the 1969-70 400 such a strong breather — got adapted onto the larger 455 block. The result was rated at 335 horsepower and a towering 480 lb-ft of torque at just 3,600 rpm, giving the ’71-’72 Trans Am a torque curve that felt completely different from the quicker-revving 400s that came before it. It’s a genuinely clever piece of parts-bin engineering, but it’s also proof that the 455 HO is a distinctly different animal from anything Pontiac offered in 1970 — not a bigger version of the same engine, but a different combination entirely.

That one-year gap is exactly where the confusion creeps in. A handful of commenters on this very video flagged visual details that don’t match a genuine ’70 car at all — honeycomb-style grille inserts that didn’t appear until 1972, and high-back bucket seats that came in with the Custom interior package starting in 1971, a year after the low-back buckets that were standard in 1970. None of that makes the car in the video fake or dishonest. It’s a common reality of 55-year-old muscle cars: parts get swapped during restorations, engines get replaced when the originals finally give up, and badges don’t always get updated to match what’s actually sitting between the fenders.

What Makes the Early Trans Am Worth the Confusion

The mix-up matters because it points at something genuinely overlooked about the early Trans Am: it earned its reputation on chassis tuning, not just displacement. Pontiac engineers built the second-generation Trans Am around a stiffer unibody, wider wheels and tires, and a front spoiler and rear wing that weren’t just decoration — they were there to keep a 3,700-pound car planted at speed. That’s the detail Raiti’s Rides keeps circling back to in the video: the Trans Am wasn’t just a quarter-mile tool. It was one of the only cars from Detroit’s muscle era that could hang in a corner, a trait that mattered more to Pontiac’s engineers than another 20 cubic inches would have.

That’s also why the engine swap debate tends to miss the point for serious collectors. A correctly documented Ram Air IV car, one of roughly 88 built, is worth a significant premium specifically because it’s rare and accurately represents what left the factory. A 1970 Trans Am wearing a later 455 isn’t lesser as a driver, but it isn’t what Pontiac built in March of 1970, either — and on a muscle car where the paperwork is half the value, that distinction is everything.

A Name Pontiac Had to Fight For

Part of why the 1970 Trans Am carries so much weight with collectors has nothing to do with engines at all — it’s the name on the decklid. Pontiac had actually used “Trans Am” as a package designation back in 1969, but only after agreeing to pay the SCCA a royalty of roughly five dollars for every car built carrying the name, since Trans-American was the sanctioning body’s own racing series. That arrangement stuck for years, which meant every early Trans Am that rolled off the line was, in a very literal sense, a car Pontiac paid a racing organization just to call by that name. It’s a strange footnote for a model that would go on to outlive the series it was named after by decades.

Pricing tells its own version of the story. A 1970 Trans Am carried an all-in sticker of roughly $4,305 — the $2,875 base Firebird plus about $1,430 just for the Trans Am package itself — at a time when the average new car in America cost well under $4,000. Buyers paying that premium weren’t just chasing a badge — they were buying into a chassis package Pontiac had engineered specifically to compete with road-course-focused rivals like the Z/28 Camaro and Boss 302 Mustang, cars that, unlike the Trans Am, could be ordered with smaller, quicker-revving small-blocks built around handling balance rather than outright torque.

Spotting a Genuine 1970 Trans Am Today

For anyone shopping a “1970 Trans Am” listing, the details above are the giveaways. A real ’70 car runs low-back bucket seats, not the high-back Custom buckets that showed up in ’71. The grille is a simple ribbed design, not the honeycomb pattern Pontiac introduced two years later. And unless the car carries PHS documentation confirming otherwise, the engine bay should hold a 400 — either the Ram Air III or the far rarer Ram Air IV — not a 455, because Pontiac genuinely didn’t build it the other way in 1970. A PHS (Pontiac Historic Services) report, pulled from the factory’s own build sheets, is the only way to confirm what a given car left the factory wearing — 1970 Firebirds came out of both the Norwood, Ohio and Van Nuys, California plants — and it’s become close to mandatory for anyone buying a numbers-matching example at real money.

None of this makes a modified survivor worthless, and plenty of great driver-quality Trans Ams on the road today carry a later-model 455 that someone dropped in decades ago for more usable torque. It just means the engine you hear running in a video titled “1970 Trans Am” might be telling a slightly different story than the year stamped on the fender — and on a car where the paperwork is half the value, that’s a distinction worth knowing before you fall in love with the wrong number.

Watch the full video above and let us know your thoughts in the comments.