While the muscle car era was ending for all other manufacturers Pontiac would rein supreme for 1973 with the introduction of the Super Duty 455, arguably one of the best engines ever to come in a domestic car. This engine was directly derived from Pontiac’s racing programs and featured forged pistons, round exhaust ports, a cam shaft with durations identical to the Ram Air IV of the ’69 and ’70 Trans Am, and a provision for dry sump lubrication. This engine was the fastest American production engine of 1973. Oddly, although this Super Duty engine was only available in the Firebird Formula and Trans Am it was the ’73 GTO that won Car of the Year in Hi-Performance Cars magazine and remains one of automotive journalisms biggest blunders. Pontiac built just one test car for the press but never released the Super Duty 455 for the GTO.
The big changes for 1973 were mostly relegated to the Trans Am. The blue or white stripes were dropped and for the first time the large Screaming Chicken decal became joined the option list. This decal would prove hugely popular and would become synonymous with the Trans Am. Colors were expanded to three with Cameo White, Buccaneer Red, and Brewster Green. The round port 455 HO of ’71, ’72 was dropped and the standard Trans Am engine became the L-75 D port 455 with the Super Duty 455 optional at a whopping $521. The base Firebird was still the only model where you could get a 6 cylinder, the Chevrolet built 250 cid inline 6 with the 350 2bbl as the only option. Esprit, as usual came with the 350 cid 2bbl standard with a 400 2bbl optional. Except for the availability of the Super Duty 455 the Formula’s offering were unchanged with the 350 2bbl from the Esprit as standard (upgraded with dual exhausts). Formula 400 added a 4bbl 400cid engine rated at 230hp. The L-75 D port 455 was the standard engine for Formula 455 with the Super Duty 455 optional. When you ordered you Super Duty with a Formula the dual snorkel hood was replaced with a bird-less Trans Am shaker hood and scoop. The shaker hood scoop was no longer functional beginning this year.
The easiest way to identify a 1973 Firebird is by looking at the front grille. New Federal impact regulations required strengthening the front bumper so the grille was moved forward in the nostrils to accommodate the new bumper hardware. The grille design was changed to a coarse rectangular grid sometimes referred to as an egg crate replacing the honeycomb pattern of 1972. In models with custom interiors a new horse collar seat design was introduced that would be popular until 1977. Lower door panels were now molded in plastic instead of carpeted. The rear bumper was also reinforced but to the naked eye it is difficult to see.