Editing Pontiac (automobile) (section)

==Engines==
{{Main|Pontiac V8 engine}}

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 V8 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 [[Overhead valve|OHV]] [[Oldsmobile]] V8 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 V8 to an OHV design delayed its introduction until the 1953 model year, however, the Buick division was introducing its new engine (Nail valve V-8) in 1953 and asked the corporation to hold back or delay Pontiac's V8 introduction until the 1955 model year which it did.

In mid-1956, Pontiac introduced a higher-powered version of its V8. 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 pre- Super-Duty V8 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. The enlarged 1956 Pontiac V8 found its way into light-duty GMC pickup trucks.

Pontiac's second-generation V8 engines shared numerous similarities, allowing many parts to interchange from its advent in 1959 to its discontinuation in 1979. Displacement ranged from {{convert|287|to|455|CID|L|1|abbr=on}}. The similarity of the engines (except for the 301 & 265 versions) makes rebuilding these engines relatively easier. This feature also made it possible for Pontiac to develop the modern [[muscle car]], by the relatively simple process of placing its second largest-displacement engine, the {{convert|389|CID|L|1|abbr=on}} into its mid-size car, the Le Mans, making the Pontiac LeMans GTO.

From their inception in the 1950s until the early 1970s, Pontiac engines were known for their performance. The {{convert|455|CID|L|1|abbr=on}} V8 was the largest and available in most Pontiacs except in the compact-size cars. At the height of the horsepower era, Pontiac engines reached ratings of {{convert|390|hp|kW PS|0|abbr=on}} (SAE gross), though other engines achieved considerably higher outputs. [[United States vehicle emission standards|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 {{convert|310|hp|abbr=on}} 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 {{convert|290|hp|abbr=on}} 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|dry-sump]] oiling.

The only non-traditional Pontiac V8 engines were the {{convert|301|CID|L|1|abbr=on}} and the {{convert|265|CID|L|1|abbr=on}}. 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 {{convert|4|in|mm|adj=on}} bore and {{convert|3|in|mm|adj=on}} stroke, identical to the 302ci.version of 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 {{convert|396|CID|L|1|abbr=on}} V8.

===Carburetors===
Pontiac used Carter 1-barrel [[carburetor]]s 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 horsepower 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 top GTO 400 engine and the 428 H-O engines the same horsepower as the 389 and 421. The new engine had redesigned cylinder heads with different valve angles and larger ports that allowed for larger diameter intake and exhaust valves.

By the end of the muscle car era, the Quadrajet setup had become common on Pontiac engines. The Quadrajet design continued until 1990 for Oldsmobile V8 applications, with added computer controls to meet emissions and fuel economy standards.