Tuesday, November 16, 2010

Pontiac GTO, 1967

Pontiac GTO, 1967

The Pontiac GTO was an automobile built by Pontiac from 1964 to 1974, and by General Motors Holden in Australia from 2003 to 2006. It is often considered the first true muscle car. From 1964 until 1973.5, it was closely related to the Pontiac Tempest, but for its final year it was based on the Pontiac Ventura. The 21st century GTO is essentially a left hand drive Holden Monaro, itself a coupe variant of the Holden Commodore.

The GTO was the brainchild of Pontiac engineer Russell Gee, an engine specialist, and Pontiac chief engineer John De Lorean. Shane Wiser was the first to think of the idea of the GTO. In early 1963, General Motors management issued an edict banning divisions from involvement in auto racing. At the time, Pontiac's advertising and marketing approach was heavily based on performance, and racing was an important component of that strategy. Jim Wangers proposed a way to retain the performance image that the division had cultivated with a new focus on street performance. It involved transforming the upcoming redesigned Tempest (which was set to revert to a conventional front-engine, front transmission, rear-wheel drive configuration) into a "Super Tempest" with the larger 389 in³ (6.5 L) Pontiac V8 engine from the full-sized Pontiac Catalina and Bonneville in place of the standard 326 in³ (5.3 L) Tempest V8. By promoting the big-engine Tempest as a special high-performance model, they could appeal to the speed-minded youth market (which had also been recognized by Ford Motor Company's Lee Iacocca, who was at that time preparing the Ford Mustang).

The name, which was DeLorean's idea, was inspired by the Ferrari 250 GTO, the highly successful race car. It is an acronym for Gran Turismo Omologato, Italian for homologated for racing in the GT class. The name drew protest from purists, who considered it close to sacrilege.

The GTO was technically a violation of GM policy limiting the A-body intermediate line to a maximum engine displacement of 330 in³ (5.4 L). Since the GTO was an option package and not standard equipment, it could be considered to fall into a loophole in the policy. Pontiac General Manager Elliot "Pete" Estes approved the new model, although sales manager Frank Bridge, who did not believe it would find a market, insisted on limiting initial production to no more than 5,000 cars. Had the model been a failure, Estes likely would have been reprimanded. As it turned out, it was a great success.

First generation

The first Pontiac GTO was an option package for the Pontiac LeMans, available with the two-door sedan, hardtop coupe, and convertible body styles. For US$ 296, it included the 389 in³ V8 (rated at 325 hp (242 kW) at 4800 rpm) with a single Carter AFB four-barrel carburetor and dual exhaust, chromed valve covers and air cleaner, 7 blade clutch fan, a floor-shifted three-speed manual transmission with Hurst shifter, stiffer springs, larger diameter front sway bar, wider wheels with 7.50 x 14 redline tires, hood scoops, and GTO badges. Optional equipment included a four-speed manual transmission, two-speed automatic transmission, a more powerful "Tri-Power" carburation rated at 348 hp (260 kW), metallic drum brake linings, limited slip differential, heavy-duty cooling, ride and handling package, and the usual array of power and convenience accessories. With every available option, the GTO cost about US$ 4,500 and weighed around 3,500 pounds (1,600 kg).

Most contemporary road tests used the more powerful Tri-Power engine and four-speed. Car Life clocked a GTO so equipped at 0-60 miles per hour (0-97 km/h) in 6.6 seconds, through the standing quarter mile in 14.8 seconds with a top speed of 99 miles per hour (158 km/h). Like most testers, they criticized the slow steering, particularly without power steering, and inadequate drum brakes, which were identical to those of the normal Tempest. Car and Driver incited controversy when it printed that a GTO that had supposedly been tuned with the "Bobcat" kit offered by Royal Pontiac of Royal Oak, Michigan, was clocked at a quarter mile time of 12.8 seconds and a top speed of 112 mph (179 km/h) on racing slicks. Later reports strongly suggest that the Car and Driver GTOs were equipped with a 421 in³ (6.9 L) engine that was optional in full-sized Pontiacs. Since the two engines were difficult to distinguish externally, the subterfuge was not immediately obvious. Frank Bridge's sales forecast proved inaccurate: the GTO package had sold 10,000 units before the beginning of the 1964 calendar year, and total sales were 32,450.

Throughout the 1960s, Royal Pontiac, a Pontiac car dealer in Royal Oak, Michigan, offered a special tune-up package for Pontiac 389 engines. Many were fitted to GTOs, and the components and instructions could be purchased by mail as well as installed by the dealer. The name "Bobcat" came from the improvised badges created for the modified cars, combining letters from the "Bonneville" and "Catalina" nameplates. Many of the Pontiacs made available for magazine testing were equipped with the Bobcat kit. The GTO Bobcat accelerated 0-60 in 4.6 seconds (this 0-60 time is now equalled by the factory 2005-06 GTO with automatic transmission and no modification).

The precise components of the kit varied but generally included pieces to modify the spark advance of the distributor, limiting spark advance to 34-36° at no more than 3,000 rpm (advancing the timing at high rpm for increased power), a thinner head gasket to raise compression to about 11.23:1, a gasket to block the heat riser of the carburetor (keeping it cooler), larger carburetor jets, high-capacity oil pump, and fiberglass shims with lock nuts to hold the hydraulic valve lifters at their maximum point of adjustment, allowing the engine to rev higher without "floating" the valves. Properly installed, the kit could add between 30 and 50 horsepower (20-40 kW), although it required high-octane superpremium gasoline of over 100 octane to avoid spark knock with the higher compression and advanced timing.

The Tempest line, including the GTO, was restyled for the 1965 model year, adding 3.1 inches (7.9 cm) to the overall length while retaining the same wheelbase and interior dimensions. It sported Pontiac's characteristic vertically stacked quad headlights. Overall weight increased about 100 pounds (45 kg). Brake lining area increased nearly 15%. The dashboard design was improved, and an optional rally gauge cluster added a more legible tachometer and oil pressure gauge.

The 389 engine had revised cylinder heads with re-cored intake passages, improving breathing. Rated power increased to 335 hp (250 kW) @ 5,000 rpm for the base 4—barrel engine; the Tri-Power was rated 360 hp ((268 kW) @ 5,200 rpm. The Tri-Power engine had slightly less torque than the base engine, 424 ft·lbf (574 N·m) @ 3,600 rpm versus 431 ft·lbf (584 N·m) @ 3,200 rpm. Transmission and axle ratio choices remained the same.

The restyled GTO had a new simulated hood scoop. A rare, dealer-installed option was a metal underhood pan and gaskets that allowed the scoop to be opened, transforming a cosmetic device into a functional cold air intake. The scoop was low enough that its effectiveness was questionable (it was unlikely to pick up anything but boundary layer air), but it at least admitted cooler, denser air, and allowed more of the engine's formidable roar to escape.

Car Life tested a 1965 GTO with Tri-Power and what they considered the most desirable options (close-ratio four-speed manual transmission, power steering, metallic brakes, rally wheels, 4.11 limited-slip differential, and Rally Gauge Cluster), with a total sticker price of US$3,643.79. With two testers and equipment aboard, they recorded 0-60 miles per hour (0-97 km/h) in 5.8 seconds, the standing quarter mile in 14.5 seconds with a trap speed of 100 miles per hour (160 km/h), and an observed top speed of 114 miles per hour (182.4 km/h) at the engine's 6,000 rpm redline. Even Motor Trend's four-barrel test car, a heavier convertible handicapped by the two-speed automatic transmission and the lack of a limited slip differential, ran 0-60 mph in 7 seconds and through the quarter mile in 16.1 seconds at 89 miles per hour (142.4 km/h).

Pontiac's intermediate line was restyled again for 1966,
gaining more curvaceous styling with kicked-up rear fender lines for a "Coke-bottle" look, and a slightly "tunneled" backlight. Overall length grew only fractionally, to 206.4 inches (524 cm), still on a 115 inch (292 cm) wheelbase, while width expanded to 74.4 inches (189 cm). Rear track increased one inch (2.5 cm). Overall weight remained about the same. The GTO became a separate model series, rather than an option package, with unique grille and tail lights, available as a pillared sports coupe, a hardtop sans pillars, or a convertible. Also an automotive industry first, plastic front grilles replaced the pot metal and aluminum versions seen on earlier years. New Strato bucket seats were introduced with higher and thinner seat backs and contoured cushions for added comfort and adjustable headrests were introduced as a new option. The instrument panel was redesigned and more integrated than in previous years with the ignition switch moved from the far left of the dash to the right of the steering wheel. Four pod instruments continued, and the GTO's dash was highlighted by walnut veneer trim. The 1966 model year is viewed by many as the most iconic of all GTOs because of its independent model status and because it was the last year Pontiac offered the 389 Tri Power engine configuration.

Engine choices remained the same as the previous year. A new rare engine option was offered: the XS engine option consisted of a factory Ram Air set up with a new 744 high lift cam. Approximately 35 factory installed Ram Air packages are believed to have been built, though 300 dealership installed Ram Air packages are estimated to have been ordered. On paper, the package was said to produce the same 360 hp as the non-Ram Air, Tri Power car, though these figures are believed to have been grossly underestimated in order to get past GM mandates.

Sales increased to 96,946, the highest production figure for all GTO years. Although Pontiac had strenuously promoted the GTO in advertising as the "GTO Tiger," it had become known in the youth market as the "Goat." Pontiac management attempted to make use of the new nickname in advertising but were vetoed by upper management, which was dismayed by its irreverent tone.

Styling remained essentially unchanged for 1967, but the GTO saw several significant mechanical changes.

A corporate policy decision banned multiple carburetors for all cars except the Chevrolet Corvette, so the Tri-Power engine was cancelled and replaced with new quadrajet four-barrel carburetor. Chevrolet was able to keep the tri-power set up to help with their image; the GTO was really becoming a serious competition problem for them. To compensate, the 389 engine received a slightly wider cylinder bore (4.12 inches, 104.7 mm) for a total displacement of 400 in³ (6.6 L). Torque increased slightly, from 431 to 441 ft-lbf (584 to 598 N·m) for the base engine, from 424 to 438 ft-lbf (575 to 594 N·m) for the optional engine but power remained the same. Testers found little performance difference, although the distinctive sound and fury of the Tri-Power was missed.

Two new engines were offered. The first was an economy engine, also 400 in³ but with a two-barrel carburetor, 8.6:1 compression, and a rating of 265 hp (198 kW) and 397 ft-lbf (538 N·m) of torque.  The package, which included a functional hood scoop (much like the previous dealer-installed set-up), featured stiffer valve springs and a longer-duration camshaft. Rated power and torque were unchanged, although the engine was certainly stronger than that of the standard 360 hp (268 kW) GTO. It was available only with 3.90:1 or 4.33:1 differential gearing, and its "hotter" camshaft left it with a notably lumpier idle and less cooperative part-throttle response.

Emission controls, including an air injector system, were fitted in GTOs sold in California only.

The two-speed automatic was replaced with the three-speed Turbo-Hydramatic TH400, which was available with any engine. When the Strato bucket seats and console were ordered, the TH was further enhanced by the use of Hurst's Dual-Gate shifter, which permitted automatic shifting in "Drive' or manual selection through the gears. It was generally considered an equal match for the four-speed in most performance aspects. Meanwhile, the Tempest's inadequate drum brakes could be replaced by optional disc brakes on the front wheels (for US$104.79, including power boost), a vast improvement in both braking performance and fade resistance.


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