Pontiac is a marque of automobile produced by General Motors and sold in the United States, Canada and Mexico from 1926 to the present. In the GM brand lineup, Pontiac is a mid-level brand featuring a more sporting, performance-driving experience for a reasonable price, and a youthful feel to its advertising.
The Pontiac brand was introduced by General Motors in 1926 as the 'companion' marque to GM's Oakland Motor Car line. The Pontiac name was first used in 1906 by the Pontiac Spring & Wagon Works and linked to Chief Pontiac who led an unsuccessful uprising against the British shortly after the French and Indian War. The Oakland Motor Company and Pontiac Spring & Wagon Works Company decided to merge together in November 1908 under the name of the Oakland Motor Car Company. The operations of both companies were joined together in Pontiac, Michigan to build the Cartercar. Oakland was purchased by General Motors in 1909. The first General Motors Pontiac was conceived as an affordable six cylinder that was intended to compete with more inexpensive four cylinder models. Within months of its introduction, Pontiac outsold Oakland. As Pontiac's sales rose and Oakland's sales began to decline, Pontiac became the only 'companion' marque to survive its 'parent', in 1932.
A Native American Headdress was used as a logo until 1956. The current Pontiac logo represents a Native American arrowhead. An alternate slang term for the marque among performance enthusiasts is Poncho. Another slang term used in the early stages of brand was "Indian" due to the subject matter of its logo.
Early years
Pontiac began selling cars with straight 6-cylinder engines. In 1933, it moved up to producing the cheapest cars with straight 8-cylinder engines. This was done by using many components from the 6-cylinder Chevrolet, such as the body. In the late 1930s, Pontiac used the so-called 'torpedo' body of the Buick for one of its models just prior to its being used by Chevrolet as well. This body brought some attention to the marque.
Pontiac developed certain stylistic trademarks, besides the 'Indian head'. Most notable of these were the 'silver streak' - several narrow strips of chrome-plated steel which extended from the grille down the center of the hood. Eventually they extended from the rear window to the rear bumper as well, but ultimately along the tops of the fins instead.
Middle years
For an extended period of time, prewar through the early 1950s, the Pontiac was a quiet and solid car, but not especially powerful. A flathead (side-valve) straight eight offered both the quietest and smoothest possible operation, with an appropriately soft suspension and quiet muffler offering the feeling of luxury without the expense. These combinations proved attractive to the vehicle's target market - a reserved lower middle class that was not especially interested in performance or handling and was seeking good value and a roomy vehicle in a step up from the entry-level Chevrolet. This fit well within parent GM's strategy of passing an increasingly prosperous customer up through the various divisions. Straight 8's are slightly less expensive to produce than the V8's that were growing in popularity, but they were also heavier and longer than a V8. Also, the long crankshaft suffered from excessive flex, which restricted straight 8's to relatively low compression and modest RPM's. In this application the inexpensive (but poorly-breathing) flat-head valves were not a liability.
Pontiac was the last of GM's North American marques to switch to the V-8. As was the case with its using straight-8, Pontiac used a cost-cutting feature on its engines. Instead of having its OHV rockers pivoting on bearings machined into them, the rockers were stamped from sheet metal into a cup shape that was fitted over a hemisphere with oil forced at high pressure between the surfaces instead. The division encouraged racers, such as Mickey Thompson's building a speed record car with four such engines, so as to get this novel design better accepted.
For a short time, its stylistic trademark doubled to two silver streaks, representing the cylinder banks. But a new image was desired for the marque, and in the meantime, there was a bit of confusion. The 1955 and 1956 Pontiacs had grilles reminiscent of Mercury and fins and taillights reminiscent of Oldsmobile. Eventually, the streaks and their grille ripples, the fins and Indian heads were all discarded in place of a split grille and a simplified red arrowhead trademark.
When Pontiac decided it needed to compete in the performance market, it made the necessary change to a V-8 with overhead valves.
Engines
Pontiac's second generation V-8 engines were nearly identical, allowing many parts to interchange from its advent in 1955 to its demise in 1979. Sizes ranged from 265 in³ to 455 in³. This similarity (except the 301 & 265) makes rebuilding these engines particularly easy, as almost any Pontiac engine one can find will contain useful parts. This dimensional similarity between engines of various capacity also made it possible for Pontiac to invent the modern muscle car, by the relatively simple process of placing its second largest engine the 389 cid into its mid-size car, the (Le Mans) creating the Pontiac GTO. The non-traditional Pontiac V8 was the 301 and the smaller displacement 265 in³. Produced from 1977 through 1981, this motor has the distinction of being the last Pontiac V8 produced by PMD. The 301 has a 4 inch bore and 3 inch stroke, identical to the vaunted Chevrolet and Ford 302 engines.
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 in³ V8.
All Pontiac Motor Division (PMD) engines (pre-1980 unified GM) were designed around a low-RPM/high-torque model, as opposed to the ubiquitous Chevrolet Small-Block engine known for its smaller displacement and high RPM/high power design. PMD engines were unique for their integrated water pump and timing chain cover, and separate valley pan and intake.
Carburetors
PMD originally used Carter 1-barrel carburetors for many years, but by the time of the second generation V-8 engines had switched mostly to the 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 half way. This was accomplished two ways, mechanically for the manual transmission models, and via a vacuum-switch on the automatics. This went through various permutations before being banned by GM.
PMD also had a square-bore 4-barrel at the time, but this was rated at a lower power than the Tri-Power. This carburetor was later replaced by the Quadrajet, a spread bore. 'Spread-bore' refers to the difference in sizes between the primaries and secondaries.
By the end of the muscle car era, the QuadraJet setup had become the nearly-ubiquitous choice on PMD engines, due to its excellent economy and power characteristics. While QuadraJets have been occasionally derided as being poor performers, with proper understanding and tuning it can compete at most levels with other designs.
This design proved good enough to last well into the 1980s with emissions modifications while most others carburetors were dropped for the easier to build fuel injection when economy mattered.
