However, that proved to be impossible due to the emissions regulations of the era. When asked about the compromises for the production SD455 engine, McCully responded, "Compression, camshaft, jetting, and vacuum advance." He followed by stating that he would have preferred a compression ratio of 10.25:1, a camshaft with 041 valve timing, slightly richer carburetor jetting, and as much vacuum advance as the engine would tolerate. Skip McCully verified that no production SD455s released to the public were fitted with the 480737 cam. This is also consistent with the 290 SAE net horsepower factory rating (as measured at the crankshaft). Forged rods and forged aluminum pistons were specified, as were unique high-flow cylinder heads.Ī production line stock SD455 produced 253 rear wheel HP on a chassis dyno, as reported by High Performance Pontiac magazine (January, 2007). Original plans called for a forged crankshaft, although actual production SD455s received nodular iron crankshafts with minor enhancements. The SD-455 consisted of a strengthened cylinder block that included four-bolt main bearings and added material in various locations for improved strength. In 19, a special version of the 455, called the Super Duty 455 (SD-455), was offered. The 1974 model year production literature listed the specifications of the production engine (290 SAE net horsepower). That rating appeared in published 1973 model year Pontiac literature, which had been printed prior to the "pre-production" engines "barely passing" emissions testing, and the last minute switch to what became the production engine. An original rating of 310 bhp (314 PS 231 kW) SAE net had been assigned to the SD-455, though that rating was based on the emissions non-compliant "pre-production" engines, as mentioned above.
Starting in 1972, and continuing until 1977, the Firebird was only produced at the Norwood, Ohio, facility.Īctual production cars yielded 1/4 mile results in the high 14 to 15.0 second/98 MPH range (sources: Motor Trend Magazine, July '73 and Roger Huntington's book, American Supercar) – results that are consistent with a 3,850 pound car (plus driver) and the engine equipped with a 4-barrel Rochester Quadrajet carburetor rated at a maximum power of 290 bhp (294 PS 216 kW) at 4000 rpm and a maximum torque of 395 lb⋅ft (536 N⋅m) at 3600 rpm figure. Again the 455HO was the only engine available for the Trans Am. The HO engine also included Ram Air IV.ĭuring a 1972 strike, the Firebird (and the similar F-body Camaro) were nearly dropped. The 455 engine was available in the L75 325 hp (242 kW) version and the LS5 335 hp HO version, which was the standard, and only engine option, for the Trans Am. The Pontiac 455 cu in (7.5 L) engine first became available in the second generation Firebird in 1971.
#1970 firebird full
The difference between the GTO and Firebird engines was that the secondary carburetor's throttle linkage had a restrictor which prevented the rear barrels from opening completely, adjusting the linkage could allow full carburetor operation resulting in identical engine performance.įor the 19 model years, all Firebirds equipped with radios had the antennas mounted "in-glass" in the windshield. There were two Ram Air 400 cu in (6.6 L) engines for 1970: the 335 hp (250 kW) L74 Ram Air III (366 hp (273 kW) in GTO) and the 345 hp (257 kW) LS1 Ram Air IV (370 hp (280 kW) in GTO) that were carried over from 1969. The new design was initially characterized with a large C-pillar, until 1975 when the rear window was enlarged. The top of the rear window line going almost straight down to the lip of the trunk lid, a look that was to epitomize F-body styling for the longest period during the Firebird's lifetime. Replacing the "Coke bottle" styling was a more "swoopy" body style, while still retaining some traditional elements. Macho Trans-Am (a package offered by the Mecham Pontiac dealership in Glendale, AZ) Trans Am Turbo NASCAR Pace Car Edition (1981) Trans Am Turbo Indy Pace Car Edition (1980)
Yellow Bird Esprit Appearance Package "W73" (1980) Red Bird Esprit Appearance Package "W68" (1978–1979)īlack Trans Am Special Edition "Y84" (1979) Gold Trans Am Special Edition "Y88" (1978) Sky Bird Esprit Appearance Package "W60" (1977–1978) This generation of Firebirds were available in coupe form only after the 1969 model year, convertibles were not available until 1991.įormula Appearance Package "W50" (1976–1981)īlack-and-Gold Trans Am Pontiac 50th Anniversary Limited Edition (1976)īlack-and-Gold Trans Am Special Edition (1977–1978, 1980–1981) The second generation debut for the 1970 model year was delayed until February 26, 1970, because of tooling and engineering problems thus, its popular designation as a 1970½ model, while leftover 1969s were listed in early Pontiac literature without a model-year identification.
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