Bird of Paradise
1973 Formula Firebird Super Duty
by Paul Herd
Gas prices soared from a quarter to a dollar a gallon, and long lines formed as drivers tried to get a few precious gallons before the sign “Out of Gas” was placed on the pump. The time was 1973 and Pontiac, who started the muscle car era in 1964 with the GTO, was singing the swan song of high performance with the introduction of the 455 Super Duty that available as an option in the Trans AM and the Firebird Formula.
Rated at 310 horsepower this power plant was all new: from the block, which
featured reinforced webbing with four-bolt mains, forged steel connecting rods, special
forged aluminum pistons, high lift camshaft, special intake and four-barrel carburetor and
header type exhaust manifolds that poured into a dual exhaust system that emitted the
better sounds than that could any thing that could be found on the radio, to the heads
which were a variation of the Ram Air IV heads with 1.77 inch exhaust valves and 2.11
intake valves. In fact it was one of the most free flowing and powerful engines that
Pontiac ever produced. Many articles and reports will hammer the fact that this engine
was built during the days of low compression, and compare it to the Ram Air IV. The
truth is that Super Duty was faster than the 400 Ram Air IV. A quarter mile run for a
1971 Trans Am with the 400-ci V-8 was 14.8 seconds while a 1973 Super Duty Trans
Am ran 13.75 seconds. If the horsepower rating methods were the same as before 1972,
the rating for the 1973 Super Duty would be more like 380-hp.
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