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1963 Corvette Z06 Race Cars - Thunder On The Green

A Pair Of Midyear Corvette Race Cars Takes Center Stage At Bloomington '06

Walt Thurn Jul 25, 2007
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The annual Bloomington Gold show in Lake Charles, Illinois, always draws an impressive lineup of the world's finest historic Corvettes. This year proved no exception when two significant Corvette race cars were presented for bidding at the show's traditional Mecum auction. Both cars competed at the '63 12 Hours of Sebring, their construction having been personally supervised by Corvette Chief Engineer Zora-Arkus Duntov just prior to the race.

Walking around these cars in the Bloomington exhibit area provided a glimpse into a veritable Corvette-racing time capsule. Compared with today's race cars, these Sting Rays look like slightly modified versions of their regular-production counterparts. But in 1963 they were state-of-the-art, factory-built competitors, ready to do battle with the world's best performance machines.

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Thanks to a detailed restoration, the No. 1 Gulf Oil Z06 appears exactly as it did at Sebring in 1963. The grotesque rear fender flares-cobbled to satisfy a last-minute FIA mandate-covered the Z's large stock-car-racing tires.

Prior to the Sting Ray, the Corvette had been unbeatable in production-car racing. Corvette Chief Engineer Zora-Arkus Duntov aimed to preserve this legacy by designing a racing version of the Sting Ray, called the Z06. This "Special Performance Package" included unique dual-circuit power brakes with sintered- metallic linings, vented backing plates, larger finned brake drums, cooling fans in the drums themselves, and self adjusters that worked moving forward instead of in reverse.

The suspension modifications consisted of a heavy-duty rear transverse spring (with seven leaves rather than nine), beefed-up front springs, and specially calibrated shock absorbers all around. Also included were a 36-gallon fuel tank and aluminum knock-off wheels. Besides the Special Performance Package, additional options were required, including a 360hp fuel-injected engine, a four-speed transmission, and a Posi-traction rearend. The Z06 option added $1,818.14 to the Corvette's $4,252.00 base price, with the other required upgrades tacking on another $661.75.

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The Z's fuel-injected 327/360 engine produced about 485 hp in race trim. With Don Yenko and Dr. Dick Thompson at the wheel, the car had serious podium potential, but mechanical problems put it out of the race early on.

Racers had high hopes for the new Z06, but these were quickly dashed when Carroll Shelby introduced a heavily reworked British roadster called the Cobra. In addition to being 1,000 pounds lighter than the Z06, the Cobra had disc brakes and an engine whose output equaled the Corvette's. Zora knew the Corvettes didn't stand a chance against the Cobras in short events, but endurance races were another story altogether. Here, he believed the Corvette's sturdy design would give it a durability advantage over the lightweight Shelby.

Zora maintained a close relationship with several of the more successful private Corvette race teams of the day. He shipped a total of six Z06 Vettes to these teams, among them the Gulf Oil and Johnson Chevrolet outfits, for the '63 12 Hours of Sebring. These cars were notable for their new two-bar knockoff wheels, which were nicknamed "tin wheels" by team members.

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One of the subtle changes engineers made to "Gulf One" involved moving the factory fuel filler closer to the rear window. This shaved eight seconds off the time required to refill the car's 37.5-gallon gas tank. Large fender scoops forced air into the rear brake drums.

When the Gulf team fitted larger tires and wheel spacers to its tin-wheeled Corvettes, race organizers responded by making the team add bulging fender flares to the cars prior to the race. The No. 2 Gulf car experienced a tin-wheel failure during practice, prompting the team to replace the wheels with factory steel units. The No. 3 Johnson Racing Sting Ray, driven by Delmo Johnson and Dave Morgan, did not get the spacers and therefore was not required to wear the unsightly flares.

The race got off to an ominous start for the Gulf team when its white No. 1 car dropped out early due to mechanical problems. Then, with only four hours left in the race, the No. 2 Gulf car pitted in a cloud of steam, the victim of a failed water pump. The No. 3 Johnson Sting Ray, meanwhile, soldiered on to finish Second in class and Sixteenth overall.

Both the No. 1 and No. 3 cars have since undergone extensive restorations and now appear just as they did at the start of the 1963 race. Not surprisingly, both received a lot of interest from the Mecum auction buyers, with the No. 3 car being bid all the way up to $1,150,000 before finally ending with a no-sale. Some 43 years after their racing debut, Zora's handbuilt Cobra killers continue to thrill.



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