General Motors surrendered itself to temptation in 1970 and lifted its 400-cid limit on intermediate models. That unleashed some of the quickest automobiles ever to come out of Detroit. The 1970 Buick GSX was among them, doing its part to make this the pinnacle year for American muscle cars.

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The GSX, an uplevel version of the GS 455, was Buick's ultimate supercar.
©2007 Publications International, Ltd.
The 1970 Buick GSX, an uplevel version of the GS 455, came with an exclusive
package of aero aids and graphics. It's one of the all-time great muscle cars. See more muscle car pictures.

At the forefront of the rush to power was none other than Buick. Its performance offering was again based on the midsize Skylark, which got fresh styling that added two inches of body length on an unchanged wheelbase for '70. Replacing the GS 400 and its 400-cid V-8 was the GS 455, named for its new 455-cid V-8.

The massive 455-cid engine had bigger valves than its 400-cid predecessor, and it produced a whopping 510 lbs-ft of torque.
©2007 Publications International, Ltd.
Functional hood scoops fed ram air induction, and the Stage 1 version of the
455-cid V-8 got a hotter cam and other tweaks to raise output from 350 bhp
to 360. It produced a brutal 510 lb-ft of torque.

The new mill offered not only advantages of displacement, but had bigger valves, better heads, and a hotter camshaft. It was rated at 350 bhp. Its prodigious 510 lb-ft of torque (at a subterranean 2800 rpm) was exceeded among production cars only by Cadillac's 474- and 500-cid V-8s.

Standard on GS models were functional hood scoops that mated to dual air-cleaner intakes. For the really power hungry, Buick offered the 455 Stage I performance package. Its tweaks included a hotter cam, even larger valves with stronger springs, ported heads, and revised carburetor jetting. Torque was unchanged, and Buick slyly put horsepower at 360, but most testers said it was over 400. A bargain at just $199, the Stage I package included a Positraction 3.64:1 axle and performance modifications to the available three- and four-speed manuals and the automatic.

A hood-mounted tachometer, Hurst four-speed shifter, and heavy-duty suspension were among the features that set apart the GSX.
©2007 Publications International, Ltd.
The GSX option cost $1,196 and included a hood-mounted tachometer,
Hurst four-speed shifter, and heavy-duty suspension.

During the model year, Buick unveiled the ultimate expression of its ultimate supercar, the GSX. It added $1,196 to the GS 455 and came in either Apollo White or Saturn Yellow set off by unique stripes and spoilers. A hood-mounted tach, Hurst-shifted four-speed, Polyglas G60xl5s on seven-inch-wide wheels, front discs, and heavy-duty suspension were included.

Stripes and spoilers were unique on the GSX, which came in Saturn Yellow or Apollo White.
©2007 Publications International, Ltd.
Apollo White or this Saturn Yellow were the only GSX color choices.

Of 687 GSXs built, 488 were ordered with the Stage 1 upgrade, which cost $113 on a GSX. A 13.38-second pass at 105.5 mph prompted Motor Trend to crown the GS 455 Stage 1 "the quickest American production car we had ever tested." Most other magazines were in the high 13s. Any way you cut it, Buick had earned its place on muscle's all-time, all-star team.

The 1970 Buick GSX
Specifications
Wheelbase, inches: 112.0
Weight, lbs: 4,000
Number built: 687
Base price: $4,880

Top Available Engine
Type: ohv V-8
Displacement, cid: 455
Fuel system: 1 x 4bbl.
Compression ratio: 10.5:1
Horsepower @ rpm: 360 @ 4600
Torque @ rpm: 510 @ 2800

Representative Performance
0-60 mph, sec: 6.5
1/4 mile, sec. @ mph: 13.8 @ 101

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