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When it comes to rare muscle cars, the Buick GS 455 Stage 1 convertible is right at the top of the list as far as performance and rarity is concerned.
In the Golden Age of the Detroit super car, the preponderance of performance vehicles came from Dodge, Plymouth, Ford, Chevy, and Pontiac. Because of this, some of the coolest rare muscle cars came from the fringe brands.
AMC, Mercury, and Oldsmobile were typically not thought of as purveyors of muscle, but when they did produce such an offering, the results were quite often extraordinary.
In previous iterations of this column, we’ve taken a look at a number of the rarest versions of these vehicles, such as the 1969 AMC AMX 390 Super Stock, the 1968 Mercury Cougar GT-E 428 Cobra Jet, and the 1969 Hurst/Olds convertible.
In an effort to promulgate the history and particulars of another decidedly scarce muscle car from a company not traditionally thought of as a performance brand, I thought that this month we’d turn our attention to Buick.
A manufacturer most commonly associated with the building of opulent road yachts of prodigious size and mass, Buick did, in fact, crank out a genuine, dyed-in-the-wool muscle cars during the Golden Age.
One such car, the 1970 Buick GS 455 Stage 1, was an incredibly scarce, asphalt-devouring monster, and thusly deserves being this month’s subject of Rare Rides!
The 1970 Buick GS 455 Stage I Convertible. (Photo courtesy of Mecum Auctions.)
The history of the Buick GS began in 1964, when the “Gran Sport” moniker was given to an options package for the 1965 Skylark. Featuring a “too large for a mid-sized car” engine – the “Nailhead” 401 cubic-inch V8, good for 325 horsepower and a impressive 445 lb-ft of torque — the Gran Sport package also included upgraded exterior and interior trim, a heavy-duty radiator, stiffer convertible frame, upgraded brakes, a front anti-sway bar, and a dual exhaust.
The Gran Sport struck a chord with performance-minded buyers seeking an alternative to Pontiac’s all-conquering GTO, resulting in 15,780 units finding new homes in its first year of production. This was a huge victory for Buick.
The genesis of the GS: the 1965 Buick Skylark Gran Sport. (Photo courtesy of Kevauto on Wikimedia Commons.)
In ’67, Buick dropped the Gran Sport moniker for the more succinct “GS” name. Further changes included making the car its own model in the Buick lineup as opposed to being a Skylark trim level, and the powertrain received a makeover. Out went the venerable Nailhead, and in came two motors. The base engine found in the GS 340 was a 340 cubic-inch, all-iron, small-block V8 rated at 260 horsepower, while the GS 400 received a brand-new 400 cubic-inch V8, good for 340 ponies.
The year 1968 saw a comprehensive redesign of the Skylark and GS, with a bold, curvy design featuring a deep body line, known as a “Sweepspear,” that curved down from the leading edge of the flanks to the front of the rear wheel arches.
Two offerings became available in 1969 that directly appealed to performance enthusiasts: the Stage 1 package for the street and the over-the-counter Stage 2 package aimed at the track.
The restyled 1968 GS 400 convertible. (Photo courtesy of MercurySable99 on Wikimedia Commons.)
Stage 1 featured a new engine, curiously referred to as the “4.3125 by 3.90-inch over square V8” in Buickspeak. It came equipped with a Rochester 4V Quadrajet carburetor and upgraded pistons, camshaft, and exhaust, which helped it to put out 350 horses and 440 lb-ft.
Stage 2 came with an even more extensive group of go-fast parts. Included were a hot cam, headers, a special intake manifold, hollow pushrods for internal weight savings, forged pistons, and an upgraded ignition. This really made the GS move, though horsepower numbers are just rumors floating on the Internet.
The 1969 Buick GS 400 Stage 1 convertible. (Photo courtesy of Bring a Trailer.)
Top Of The Mountain
The 1970 model year was the zenith of the Golden Era of muscle. It was the year that horsepower and performance figures hit their highest levels, and, for whatever reason, aesthetics seemed to reach their peak across the manufacturers as well.
While Plymouth and Dodge launched their muscular E-Body Barracuda and Challenger models, Pontiac tweaked The Goat for even more performance, and Chevy bestowed its Chevelle SS with its most brutish big-block yet, the 450-horse LS6, Buick released a heavily redesigned GS and a high-performance variant destined to rise to the apex predator role in the muscle car wars. It went by the name of the Buick GS 455 Stage 1.
The redesigned 1970 Buick GS 455 Stage 1. (Photo courtesy of Mecum Auctions.)
Buick pulled out all the stops for their latest and greatest muscle car, and this began, naturally, with a refresh of the GS’s aesthetics.
Starting up front, a deeply recessed, split grille replaced the gaping maw found on the previous generation’s face. A large GS badge resided in the lower corner of the driver-side section, while brightwork surrounded the entire unit. A pair of twin headlamps flanked either side of the grille, and a large, chunky, chromed bumper, equipped with dual parking lamps, resided immediately beneath all this.
The functional induction hood scoops. (Photo courtesy of RK Motors.)
A sculpted hood, with functional twin scoops that fed cool air directly into the engine, extended back to a steeply raked windshield.
The car’s flanks were simplified, with the audacious Sweepspear going the way of the Dodo, replaced by a gentle character line that nearly ran the entire length of the car, bisecting the radiused wheel arches along the way.
Note that for 1970, Buick saw fit to remove the “Sweepspear” body contour in favor of much cleaner and simpler flanks. (Photo courtesy of Mecum Auctions.)
The greenhouse, devoid of vent windows, featured interestingly shaped, trapezoidal quarter-windows and a buttressed, semi-fastback, trailing end. A heavily-sloped decklid led to a rather conservative rear, which was adorned with twin taillights enveloped in a mammoth, chromed bumper that also contained the license plate pocket.
Put simply, the new GS was a very attractive car, with equal measures of muscularity and elegance blended into the design.
The 1970 Buick GS 455 Stage 1 convertible’s interior was plush by period standards, (Photo courtesy of RK Motors.)
Inside, the ’70 GS 455 sported a fairly plush interior as far as muscle cars of the time were typically outfitted. The dashboard was a straight-across design and featured instrumentation presented to the driver via three square pods. Bench seats were standard, but buckets could be had for an extra charge. Also available was a center console, forced “Comfort-Flo” ventilation, air conditioning, optional power everything, a rally clock, three available steering wheels including a Rim Blow version, and a choice of radios and tape decks.
It was what lurked under the hood when one paid an extra $199 for the Stage 1 package though that helped the 1970 GS make its bones with enthusiasts and stoplight dragsters across the country.
The heart of the beast. Buick’s 455 cubic-inch V8 with the Stage 1 upgrade. (Photo courtesy of Mecum Auctions.)
Stage 1 took the newly developed 350 horsepower 455 cubic-inch V8 behemoth from the GS 455 to an elevated level. It was bestowed with a nodular-iron crankshaft linked to cast-aluminum alloy pistons by way of forged-steel connecting rods. These pistons rode back and forth in a 4.3125-inch diameter bore, travelling 3.90 inches from one end to the other, with a healthy compression ratio of 10.0:1.
A hydraulic camshaft sported 0.490 inches of lift with 326/346 degrees intake/exhaust duration, and 90 degrees of overlap. Cast iron heads contained 2.125/1.755-inch intake/exhaust valves, fully an eighth of an inch larger in diameter than those found on the non-Stage 455. A dual-snorkel air induction system fed air from the aforementioned hood scoops into a lone Rochester Quadrajet four-barrel carb atop of a dual-plane, cast-iron intake manifold.
The redesigned front end of the 1970 GS 455 Stage 1 was both muscular and elegant. (Photo courtesy of the Premier Auction Group.)
A heavy-duty radiator, a revised oil pump, and 2.25-inch diameter, low-restriction, dual exhausts topped off the Stage 1 goodies.
Buick claimed that all these upgrades generated just 10 additional horsepower over the base 455’s rating of 350.
The Stage 1 mill also produced an astonishing 510 lb-ft of twist at a low 2,800 rpm. Incredibly, was the record for the most torque in an American muscle car until 2003, when the Dodge Viper’s V10 finally eclipsed it.
When outfitted with the four-speed Muncie transmission, the robust shifter with a cue ball knob was mounted directly to the floor, or in a console if the car was so equipped. (Photo courtesy of Mecum Auctions.)
Three transmissions were available for GS 455 Stage 1 buyers to choose from. Standard was a basic, all synchro three-speed manual, while a $185 close-ratio Muncie four-speed with an 11-inch diaphragm clutch was available for folks who wanted an upgrade but still preferred to row their own gears.
For the two-pedal set there was the $227 RPO M40 Turbo Hydramatic three-speed slushbox featuring a high-upshift governor, an extra clutch in the front drum, and recalibration for firmer gear changes.
The 1970 GS 455 Stage 1 convertible was largely a sleeper, with these diminutive fender badges one of the few ways to tell that this wasn’t your grandma’s Buick. (Photo courtesy of Mecum Auctions.)
Putting the power to the ground was a GM 10-bolt rearend. Standard gearing was 3.64:1, except when air conditioning was fitted, necessitating a swap to a 3.42:1 cog. Optional factory ratios included 2.93, 3.23, and 3.91 gears, while a dealer-installed 4.78:1 ratio was available. A Positive Traction LSD was standard on Stage 1 cars.
Featuring stiffened, 142-pound front coil springs, the GS 455’s perimeter-framed suspension came with 1-inch Delco shocks at all four corners. In front lived a 0.97-inch stabilizer bar and firm control arm bushings, while out back, the rear axle was located via four firmly bushed control arms and 144-pound springs. An optional Rallye Ride Control package added a 0.875-inch rear stabilizer bar in addition to boxed lower control arms.
While the standard wheels and rubber were fairly pedestrian, a buyer had plenty of factory upgrades they could choose from, including 15″ chromed wheels and Goodyear Super Wide Oval tires. (Photo courtesy of RK Motors.)
For slowing their beast down, Buick thoughtfully provided what was, in 1969, a potent braking system. Standard equipment was 9.5×2.5-inch finned front drums with liners made of cast-iron, and 9.5×2.0-inch composite cast-iron drums in the rear. For a reasonable $64, buyers could upgrade to a power-assisted front disc brake system with big 11-inch vented rotors.
Standard GS wheels and rubber consisted of rather uninspiring G78-14 Wide Oval tires mounted to a 14x6JK steel wheels, but they could be replaced with G60-15 Super Wide Oval Goodyear Polyglas meats on 15x7J wheels of various designs and materials.
Top up… (Photo courtesy of Mecum Auctions.)
Steering was courtesy of a 24:1 manual system, but for $121 buyers could, and mostly did, opt for a variable-ratio, inline rotary valve, integral Saginaw power steering system. It yielded a 16:1 ratio on center, 12.4:1 at full lock, and 3.4 turns from lock to lock.
Thanks to all of the high-performance gear Buick thought to bestow upon the GS 455 Stage 1, and that resultant 510 lb-ft torque figure, it was one of the quickest and best handling cars of the era, right up there with the Hemicudas and big-block GTOs, Chevelles, and Mustangs.
…and top down. (Photo courtesy of Mecum Auctions.)
A major automotive periodical of the time was able to achieve a zero-to-sixty time of 5.7 seconds, and a trip through the quarter-mile that only took 13.38 seconds at 105.5 mph – supercar numbers for the era.
Despite its thrilling looks and performance, the Stage 1 was not a massive hit in the marketplace, mostly because of its rather extravagant price tag of $4500 for a modestly equipped example, as well as the exponentially increasing cost to insure cars like it at the time.
From any angle, the 1970 Buick GS 455 Stage 1 convertible looked the part of a predator for the street. Today’s collectors understand this, and are willing to pay large sums to acquire these cars. (Photo courtesy of Mecum Auctions.)
As such, only 2,465 GS455s with the Stage 1 package were built. Of those, ones featuring the car’s costliest option – the $229 power convertible top with additional chassis bracing included – were an even rarer unicorn. According to most reliable sources, convertible Stage 1s only rolled out of the factory 232 times.
Owing to the model’s beauty, performance, and rarity, prices of 1970 Stage 1 convertibles have risen to the point of being playthings for the wealthy only, with a fully restored, concours quality example fetching $236,500 at a recent auction.
Surely quite a bit of money, but understandable given the 1970 Buick GS 455 Stage 1s status as one of the Golden Era’s great Rare Rides.
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