At the height of the horsepower era, Pontiac engines reached ratings of (SAE gross), though other engines achieved considerably higher outputs. Federal emissions laws eventually brought the horsepower era to a close and resulted in a steady decline for Pontiac's engines. One holdout to this industry-wide slide was the Super Duty 455 engine of 1973–1974. Available only in the Firebird Formula and Trans Am models, this was rated at net initially but after having issues passing EPA emissions tests, the camshaft was changed to the old RA III cam, and with the change, came a net rating. The engine was the pinnacle of Pontiac engine development and was a strong performer that included a few race-specific features, such as provisions for dry-sump oiling. The only non-traditional Pontiac V8 engines were the and the . Produced from 1977 through 1981, these engines had the distinction of being the last V8s produced by Pontiac; GM merged its various brands' engines into one collectively shared group in 1980, entitled General Motors Powertrain. The 301 had a bore and stroke, identical to the Chevrolet small-block engine and Ford Boss 302 engine. Pontiac engines were not available in Canada, however, but were replaced with Chevrolet engines of similar size and power, resulting in such models as the Beaumont SD-396 with a Chevrolet big-block V8. Carburetors Pontiac used Carter 1-barrel carburetors for many years but, by the time of the second generation, the V8 engines had switched mostly to 2-barrel offerings. These also were the basis for the Tri-Power setups on the engines. The Tri-Power setup included one center carburetor with idle control and two end carburetors that did not contribute until the throttle was opened more than halfway. This was accomplished two ways, mechanically for the manual transmission models, and via a vacuum switch on the automatics. This went through various permutations as it was only a factory-installed option from 1957 through 1966. Pontiac also had a square-bore 4-barrel at the time, but this was rated at lower horepower than the Tri-Power. This carburetor was later replaced by the Quadrajet, a spread bore. The term "Spread-bore" signifies the difference in sizes between the primaries and secondaries, using smaller primaries paired with larger secondaries for increased airflow at wider throttle with fuel delivery changes akin to the two-plus-four benefit of Tri-Power but with a single carburetor. The Quadrajet was not the only thing that gave the