The original muscle car era is usually defined as ending in 1974, but that’s being generous. Thanks to stricter emission controls, most other American muscle cars had long since lost their thunder by then.
2In truth, the muscle car era stretched as late as 1974 because of one car, a lone hold-out that could mix it up with almost any favorite from the 1960s – the Pontiac Trans Am with 455 Super Duty V8.
Much like the best of the earlier supercars, the spec sheet for the 1973-1974 SD-455 reads like a racing engine.
The Super Duty’s block was reinforced for greater rigidity and was fitted with 4-bolt main caps.
The connecting rods were made of forged steel, rather than cast, and were heat-treated and shot-peened for greater strength.
They were teamed with forged aluminum TRW pistons, yielding an 8.4:1 compression ratio.
The SD’s round-port cylinder heads were given particular attention by Air Flow Research to maximize airflow, of which the 800 cfm Quadrajet carburetor and cast iron, header-style exhaust manifolds took every advantage.
This Rare Low Production Firebird Trans Am With The 455 SD Engine Was Arguably The Last High Performance Engine Of The Original Muscle Car Generation. With Only 212 Produced With Four Speed Transmission..
The history of the Super Duty is legendary. However, a little-known fact is that all the 455 Super Duty engines were literally hand-built race engines, as an off-assembly line operation.
This was unheard of for a production vehicle, especially during the time of detuning and emissions regulations. Included in this car is a copy of the Pontiac Division Build Sheet, original owner’s manual, warranty booklet, a copy of the window sticker from Pontiac Historical Services and a copy of the original title from the original owner, dated August 1974.
The 1974 SD-455 Trans Am is a milestone car that marked the end of an era and almost single-handedly closed the 1964-1974 chapter in muscle car history with a bang.
The Trans Am went on to greater fame and higher sales as the 1970s progressed, but it never again reached the tire-smoking heights of the 1974 Super Duty.