1963 Corvette ZO6 Tanker – Part 1

Dave Matlock’s 1963 Z06 Tanker Sting Ray: Born to Be A Race Car and a Collector Car!

Article by K. Scott Teeters

Dave Matlock of Montgomery, Texas, is no stranger to Corvettes. The 1963 Z06 Corvette Sting Ray Tanker is Matlock’s ninth Corvette. Matlock was always a big fan of C2 Corvettes, especially the 1963 Split-Window Coupe, and was well versed in the uniqueness of the 1963 RPO Z06 “Racer Kit” option. Only 199 1963 Corvettes were built with the Z06 option. In the car collector world, low production numbers make a huge difference when it comes to a restored car’s value. The only way a 1963 Z06-optioned Sting Ray can be worth even more is if it was originally built with the $202 RPO-N03 36-gallon fuel tank. Z06 Corvettes with this option are referred to as “Tankers” because of the oversized fiberglass tank. Yes, a “fiberglass” tank. The flexible bladder tank wasn’t patented until October 19, 1965.

When Matlock found his Tanker in 1995, the Z06 was just an obscure racer option that very few knew about. But Matlock knew full well what the car was all about. The fact that it had been damaged and in storage for 20 years didn’t matter at all. What he didn’t know was that it would take 20 years to finally buy the car. Many times, buying a car with pedigree can be torturous; Matlock’s purchase was no exception. When he finally acquired the car, it went directly into restoration. But as much as Matlock already knew about the 1963 Z06, the restoration process was a process of discovery with some amazing finds.

Even though the 1963 Z06 was a one-year-only option; and there have been many more powerful, raucous Corvettes since then; it is still a significant chapter in the Corvette’s racing history. In Part 1 of this story, we’ll get into why the Z06 was created and what is so special about the car. In Part 2, we will unpack Dave Matlock’s restoration story.

Ever since the introduction of the 2001 Z06, there’s been an increased emphasis on the structure of the Corvette. The C5 Corvette was arguably the most radical new Corvette ever offered to that point and provided a stunning platform for Chevrolet’s first official Corvette Racing Team. Since then, the Z06 has become the performance darling of the Corvette community thanks to its extremely track-ready package. The C6 and C7 Z06 Corvettes were the foundation of the production of Grand Sport Corvettes and the performance flagship ZR1 Corvettes.

But when the 2001 Z06 came out, only fans of early ’60s Corvette racing knew the Z06 story. After all, in 1963, it was an expensive, $1,818.45, one-year-only option on top of a Cadillac-priced sports car. The Z06 was, to that point, the most advanced of Zora Arkus-Duntov’s “Racer Kit” series of go-fast parts, designed by Chevrolet engineers specifically for Corvette racing. The package included the latest version of Chevrolet’s $430 fuel-injected 327/360-horsepower engine (RPO L84), plus special suspension and brakes, and an optional 36-gallon fuel tank.

The Racer Kit RPO program began in 1957 and was driven by Zora Arkus-Duntov and co-engineer Mauri Rose. Duntov was the Corvette engineering lead man in Detroit, and Rose was the field engineer that worked with select racers and master mechanic and racing wizard Smokey Yunick. The racing parts were made available through the local Chevrolet Parts Department and were not shown in the sales brochures; you had to know what to look for in the parts catalog.

Unlike modern Z06 Corvettes, there were no external indications that the new 1963 Z06 Sting Ray was any different from a regular new Corvette. There was no unique hood, fenders, wheels, or badges aside from the standard “Fuel Injection” badge on the front fender. Also, RPO Z06 was ONLY available with the L84 Fuelie, unlike the modern Grand Sport that uses the standard Corvette engine, Z06 suspension, brakes, wheels, and tires. In 1963, if you wanted the racing suspension, you had to get the Z06 with the Fuelie engine. Ambitious customers “could have” ordered the parts and installed them themselves, but there’s no indication that anyone ever did that.

The Z06 package was supposed to include the optional lightweight aluminum Kelsey-Hayes knock-off wheels. While aluminum wheels are no big deal today, in 1962, this was new territory. The lightweight wheels had problems with the tires holding air and the wheels coming off at speed! Official records show that 13 sets of the $322 RPO P48 Cast Aluminum Knock-Off wheels were sold. Several sets were sent to racers, with the early 2-bar spinners and later the 3-bar spinners. Even a few racers had problems with wheels coming off because the spinners weren’t tightened properly. This was the main reason the knock-off wheels were discontinued after 1966.

The big news for the Z06 package was the improved suspension and brake parts to go along with the vastly improved 1963 structure. The new Sting Ray had an all-new perimeter steel frame with a built-in roll cage (for the coupes), a lower center of gravity, and four-wheel independent suspension with stiffer front and rear springs, larger shocks, and anti-sway bars. The 1963 version of the Fuelie (RPO L84) was improved thanks to an all-new plenum chamber intake manifold and larger fuel injector nozzles. Power was the same as the 1962 327 Fuelie at 360 horsepower; however, Corvette fuel-injection expert John DeGregory claims that on the dyno, the 1963 Z06 L84 Fuelies delivered 15-additional horsepower than the regular production 1963 Fuelies.

The complete Z06 package was supposed to carry the torch for Corvette privateer racers. But another performance sports car got in the way; the Shelby Cobra. In retrospect, the Z06 Corvette and the Cobra should have been in different classes because of the Cobra’s 1,000-pound weight advantage. A stripped-down for racing Z06 weighed around 3,000 pounds; the Shelby Cobra weighed around 2,000 pounds.

Duntov was a racer first and a Chevrolet engineer second. In retrospect, he used his position inside Chevrolet to build race cars whenever he could get away with it. Duntov was a true misfit inside G.M. and was nearly fired many times in his 21 years of employment in the Chevrolet Engineering Department. But Duntov knew who was whom and what was what in the world of auto racing.

In the summer of 1961, Duntov heard that Dave MacDonald and Jim Simpson were building a Max Balchowsky purpose-built tube-frame car with the 7/8’s scale 1961 Corvette body the guys hand-made. Just to see what the young racers were up to, Duntov visited MacDonald at his El Monte, California home garage where the car was being finished. MacDonald’s kid brother Doug was there, doing his best to stay out of the way. What Doug recalled most about the silver-haired old guy was that he could hardly understand Mr. Duntov, but his brother Dave seemed to have no trouble with Zora’s thick accent.

While tube-frame purpose-built race cars were not uncommon (think of them as early versions of modern Trans-Am cars), Duntov’s visit to MacDonald might have been the thought seed for Zora’s “Lightweight” Corvette, later known as the Grand Sport. We’ll never really know. It is ironic that it was Carroll Shelby that suggested to MacDonald and Simpson that they get a Max Balchowsky tube chassis car.

Early in 1962, Duntov learned about Shelby’s Cobra and clearly knew that his Z06 Racer Kit optioned Sting Ray would be no match for the lightweight 2,000-pound Ford-powered Cobra. Because Duntov was not officially allowed to build and race cars under the Chevrolet banner, he relied on privateer racers to “field test” (race) the latest, greatest offerings through the RPO program. Duntov arranged to have the first ten Z06 Corvettes off the St. Louis assembly line to go to select west coast racers that included; Mickey “Mr. Speed” Thompson, Bob Bondurant, Doug Hooper, Jerry Grant, and Dave MacDonald.

Thompson was “The Man” in racing in the 1960s. Known as “Sir Mick,” Thompson was a hard-charging racer, engineer, and innovator. In 1954 Thompson built the first slingshot dragster and had a series of multi-engine drag racing cars through the late ’50s. His big claim to racing fame came on September 8, 1960, when his Pontiac-powered, supercharged four-engine Challenger-I ran 406.60 mph on the Bonneville Salt Flats. Through the ’60s and ’70s, Thompson was golden with a long series of race cars; Indy cars, speed record cars, off-road 4WD trucks, dragsters, funny cars, and a successful speed parts and tires business.

Duntov had five Z06 Corvettes air freighted to Thompson’s shop in California. The other racers were flown to St. Louis to take delivery of off-the-assembly-line Z06 Corvettes to be driven back to California for a road trip break-in. Dave MacDonald’s wife Sherry later reported that while driving their Z06 across the desert, she had the car up to 140 mph with Dave yelling at her, “Go faster! Go faster!”

In less than two weeks, the Z06 Corvettes were quickly prepped for racing and entered into the 1962 Los Angeles Times Grand Prix at Riverside Raceway on October 14, 1962. The debut outing would have been spectacular for Chevrolet were it not for one lone Cobra. The Z06 Corvettes were thrashed and bashed and, in the end, came in 1st place only because Bill Krause’s Cobra broke a rear axle. With the lone Cobra out, Doug Hooper, diving one of Thompson’s Z06 Corvettes, took 1st place. While a “win-is-a-win,” it was obvious that the Z06s could not keep up with the Cobras. Duntov’s Plan B was his Lightweight (Grand Sport) program, but that’s another story.

A total of 199 Z06-optioned 1963 Corvettes rolled off the St. Louis assembly line, with 63 Z06s optioned with the 36-gallon fuel tank. Most of the cars were raced, and a few never saw action on the track. The Z06 was designed as an “Off-Road Use Only” (racing) car and was never intended to be a street Corvette. On the street, the Z06 wasn’t any quicker or faster than a Fuelie 1963 Sting Ray. The Z06 parts gave customers a stiffer suspension and improved drum brakes with elephant-ear air scoops and special fans mounted to the inner side of the vented back plates. The brake setup provided more venting and cooling for the brakes, special finned drums to displace heat, and aircraft-caliber Cerametalix linings with a total of 68 brake pad pucks riveted to the four brake shoes. The pad puck count is 16 on each rear wheel (32 total), plus 18 pucks on each front wheel (36 total) for a grand total of 68 pad pucks for all four brakes.  While not as good as disc brakes, the special brake setup was better than previous Corvette brakes that were universally not liked. Disc brakes for Corvettes would not be available until the 1965 Corvette was released.

The most successful of all of the 1963 Z06 Corvettes was the Grady Davis Gulf One car. The Gulf One car saw more track action than any of the other “assigned” Z06s. The car’s first outing was at the 1963 Puerto Rico Grand Prix, where Thompson drove it to its first-class win. In January 1963, it won at the Refrigerator Bowl in Marlboro, Maryland. The car was then prepared for FIA rules to race at the Daytona Continental and Sebring. Thompson drove it to third overall and first in GT3 at Daytona, but the transmission broke at the Sebring race in March.

Thompson went on to score wins at the SCCA’s President’s Cup race in Marlboro, in the A/Production class at Danville, Virginia, and Road America in Elkhart Lake, Wisconsin. With proper preparation and a skilled driver that wouldn’t push the car too hard, the Z06 could be competitive but didn’t deliver the big jump in track performance that Duntov anticipated. Corvette racers would have to wait till 1967 to get the bad-ass 427 L88 engine. In August 2008, the Gulf One No. 2 ’63 Corvette Z06 racer sold at auction for a whopping $1,050,000!

Unlike the C1 Racer Kits that were available from 1957 to 1962, the Z06 was a one-year-only option. The limited number of cars built has played a big part in the current value of the 1963 Z06 Corvettes. The L84 327 Fuelie small-block engine was pretty much maxed out, so perhaps, given the lay-of-the-land in 1963, Duntov didn’t see the point of the continuing development of the Z06. The big-block program and disc brakes were in the works by 1963 but weren’t ready until the 1965 Corvettes came out. Duntov likely decided, “Let’s wait a bit until we get better brakes and more power.”

So, what of the 199 Z06 Corvettes built? Skip Sofield purchased our feature car through Star Chevrolet in East Orange, New Jersey. Sofield worked for Star Chevrolet and was “the” Corvette man at Star Chevrolet. Sofield was the east coast “Mr. Corvette.” (Dick Guldstrand was the west coast “Mr. Corvette”) Upon taking delivery of the Z06, Sofield prepared the car for racing. The Z06 was never used as a street Vette while Sofield campaigned the car and had some regional success with the car until the end of the season when the front end was seriously crunched. Sofield was a racer, not a collector, so from his perspective, the Z06 was finished, a used-up, damaged race car, and retired “as-is.” Sofield then bought a 1964 Sting Ray coupe and continued his racing activities.

Eventually, the car was oddly put back together (we’ll get into the specifics in Part 2) and sold as a street Corvette. For years the stealth Z06 was just a driver 1963 Split-Window Coupe Sting Ray. Generally, in 1963 and 1964, Corvette fans were not excited about the rear split window, and many saw the 1964 version as a vast improvement. This may be hard to believe, but some ’63 Split-Window Coupes had the split-window replaced with an after-market Plexiglas window that looked like the window on all ’64 to ’67 Sting Rays! So, even though the car was a Z06 and once a race car, no one knew or really cared about the uniqueness of the car.

The same thing happened to the 1960 Cunningham Le Mans Corvettes; after the cars were raced at Le Mans, they were converted back to street duty and sold. Future owners didn’t have a clue that their cars were once raced at Le Mans! Corvette Racing and Development was moving at such a fast pace; no one cared about using up old Corvette racers. The five original Grand Sport Corvettes suffered the same “used-up racer” fate. No one knew that one day, the Z06 Sting Rays would be extremely valuable.

Restoring an old car is a process of discovery that can sometimes go beyond what’s found after the paint has been stripped off and everything has been disassembled. Dave Matlock found a treasure trove of information and memorabilia connected to his 1963 Z06 Corvette that we will share with you in Part 2 of this story which will be in the June issue of Vette Vues. Dave also has a harrowing story to share about what happened one day when he decided to take his Z06 out for a drive. He got an experiential education as to why the Z06’s brakes were designated “Off-Road Use Only.”

Here are some other Vette Vues blog posts you might enjoy:

Legendary Design: 1963 Corvette Specifications, History, and Photos

The 1963 Corvette Fuel Injected Coupe made Vete Vues Top Ten Most Desirable PERFORMANCE Corvettes. Check out our article.

You might also enjoy seeing a video for the 1963 Corvette test. Legendary Zora Arkus Duntov handpicked top Corvette racers to test drive the all-new 1963 ZO6 Corvette Stingray. He chose Dave MacDonald and Dick Thompson. This is a video of the historical test.

You might also enjoy 1963 CORVETTE GRAND SPORT VIDEOS: A SET OF 4

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