Pontiac - Engines

Engines

Pontiac engineer Clayton Leach designed the stamped steel valvetrain rocker arm, a simplified and reliable alternative to a bearing-equipped rocker. This design was subsequently picked up by nearly every OHV engine manufacturer at one point or another.

Pontiac began work on a V-8 configuration in 1946. This was initially intended to be an L-head engine, and 8 experimental units were built and extensively tested by the end of the 1940s. But testing comparisons to the OHV Oldsmobile V-8 revealed the L-head could not compete performance-wise. So, in addition to building a new Pontiac Engineering building in 1949–1951, the decision to re-direct the V-8 to an OHV design delayed its introduction until the 1955 model year.

In mid-1956, Pontiac introduced a higher-powered version of its V-8. Among other things, this version of the engine was equipped with a high-performance racing camshaft and dual 4-barrel carburetors. This was the first in a series of NASCAR-ready Super-Tempest and Super-Duty V-8 engines and introduced the long line of multi-carburetor equipped engines that saw Pontiac become a major player during the muscle car and pony car era of the 1960s. Interestingly, the enlarged 1956 Pontiac V8 found its way into light-duty GMC pickup trucks.

Pontiac's second generation V-8 engines shared numerous similarities, allowing many parts to interchange from its advent in 1959 to its demise in 1979. Sizes ranged from 265 cubic inch to 455 cubic inch. This similarity (except the 301 & 265) makes rebuilding these engines relatively easier. This feature also made it possible for Pontiac to invent the modern muscle car, by the relatively simple process of placing its second largest-displacement engine, the 389 cid, into its mid-size car, the Le Mans, creating the Pontiac GTO.

From their inception in the 1950s until the early 1970s, Pontiac engines were known for their performance. The largest engine was a massive 455 cubic inch V-8 that was available in most of their mid-size, full-size and sports car models. At the height of the horsepower era, Pontiac engines reached a powerful 390 rated horsepower (SAE gross), though other engines achieved considerably higher outputs in actuality. 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 310 hp (230 kW) 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 290 hp (220 kW) net rating. The engine was the pinnacle of Pontiac engine development and was a very strong performer that included a few race-specific features, such as provisions for dry-sump oiling. This engine and its legacy drive the SD Trans Ams and Formulas as one of the more, if not the most, desirable Pontiacs ever produced.

The only non-traditional Pontiac V-8 engines were the 301 cubic inch and the smaller displacement 265 cubic inch V-8s. Produced from 1977 through 1981, these engines had the distinction of being the last V-8s produced by Pontiac; GM merged its various brand's engines into one collectively shared group in 1980, entitled General Motors Powertrain. Interestingly, the 301 had a 4-inch (100 mm) bore and 3-inch (76 mm) stroke, identical to the vaunted 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 interesting and unusual (at least to American car fans) models as the Beaumont SD-396 with a Chevrolet big-block 396 cubic inch V-8.