40 years ago, this secret Shelby was built for high-speed stealth
Words And Photos: C. Van Tune
What’s a Cannonball?
“Cannonballing” has grown to become a word to describe any sort of high-speed endurance driving on public roads, but it has its roots in an actual event.
Not bearing much resemblance to the farcical movie The Cannonball Run that followed, the actual event was officially known as the Cannonball Baker Sea-to-Shining-Sea Memorial Trophy Dash.
Created by automotive writer Brock Yates in 1971, the secret event was an invitation-only challenge to see who could drive from New York City to Redondo Beach, California, in as quick of an elapsed time as possible. Cars left at one-minute intervals from the Red Ball Garage in Manhattan. Many of them never made it to the finish line, or without a serious encounter with law enforcement.
Time capsule of car and driver, in photos from 1982 and 2016. The Shelby has been hidden away in storage since 1987 and only just uncovered for this exclusive article.
You are looking at a legend.
The story of this special Shelby, and its mysterious owner known only by initials “RPM,” date back to 1975, when the car was found abandoned in a field on a Wyoming farm. Its original 428 Police Interceptor engine was missing, a 390 in its place, but even it was lying dead with a connecting rod stuffed through the block. When RPM drove past in his lineman’s work truck, the unloved 1967 Shelby GT500 caught his eye. An idea was born.
Forty years ago, America was in a frustrating time of boring cars, long lines to buy gasoline, and a legion of law enforcement eager to ticket anyone exceeding the ridiculous 55 mph national speed limit. It was a dark automotive era of 165-hp Corvettes, lame Mustang IIs, and smogged-out land barges.
There were no cell phones, GPS navigation systems, or on-board computers. The only social network was a CB radio, and the only technology to beat a cop’s radar gun was a simple one-band radar detector and your fast reflexes to hammer the brakes.
So, what if that forlorn GT500 could be resurrected from the dead, and built to be faster than ever? What if it could be turned into the automotive equivalent of a stealth aircraft? And what if RPM could safely drive it from coast to coast as quickly as possible?
To be a successful Cannonballer — a person with the passion to see just how fast, and how far, he could go on public highways — took ingenuity as much as guts.
But, anyone can break the speed limit. Only a very few can do it safely, and undetected, for nearly 3,000 miles, in clandestine cross-county power runs made just for the thrill of it. To paint a “1” in front of “55” on those speed limit signs.
Hidden away since 1987, this secret Shelby has been discovered, uncovered, and presented exclusively here for Power & Performance News. It is a time capsule of technology, engineering ingenuity, and how one man built it to beat the system. This is the legend of RPM’s 1967 Shelby GT500.
Part James Bond gadgetry, part Stealth Bomber technology, and packed with long-legged highway performance, the midnight blue GT500 was unlike any other car on earth (see images above).
But, let’s start at the beginning of this amazing story: The day RPM first glimpsed the Shelby, as he drove past the Gillette, Wyoming, farm where it sat abandoned.
“The first thing I saw was the upper side scoops on the car,” RPM recalls. “The grass in the pasture was about four feet tall, and the car was buried up to those scoops. I stopped my truck and climbed over the fence to get a closer look. It was covered in that red Wyoming dust, and had been sitting there long enough that the dust layer helped preserve the car.
“Back in 1975, a Shelby with a dead engine (and not even the correct engine at that) was just another used car that needed a lot of work. Selling new in 1967 for about $5,000, the moribund car that RPM found was worth maybe $500.
Even though the Shelby was only 8 years old, a DMV check revealed it had six previous owners. “It had seen a lot of hard performance use,” RPM added. ”Everyone had their fun with it, busted it, and couldn’t afford to fix it.”
The original Top Loader was gone, and a rebuilt gearbox in its place. The interior was worn, but it was all there. The original paint had seen better days, but the body was fairly straight, and all the Shelby fiberglass parts were in place.
“My original plan was to rescue the car and restore it,” RPM remembered. “The first job was to install a rebuilt 428 Police Interceptor. Luckily, the original Shelby intake manifold and dual fours had been transferred to the 390 engine before I got the car, so I restored those and put them on the 428.”
An important item to keep in mind: Forty years ago, there wasn’t anywhere near the abundance of aftermarket and restoration parts for a Shelby Mustang as there is today. Lots of ingenuity was required to make the car into the multiple-show champion it became. The first car show entered was in Salt Lake City in 1977, where it won “Best of Show.”
But, it was an article in the Shelby American Automobile Club’s magazine in 1979 that caught RPM’s attention, and changed his plans forever.
“The story that SAAC president Rick Kopec wrote about driving his ’65 GT350 in the 1979 Cannonball cross-country race got me to wondering if I could learn enough to develop a special vehicle to compete in such an event,” RPM told us. “A vehicle that would be fast, reliable, and stealthy enough to avoid all of the known, and unknown, obstacles on the nearly 3,000 miles of highways and backroads.
“Cannonballing” has grown to become a word to describe any sort of high-speed endurance driving on public roads, but it has its roots in an actual event. Not bearing much resemblance to the farcical movie “The Cannonball Run” that followed, the actual event was officially known as the Cannonball Baker Sea-to- Shining-Sea Memorial Trophy Dash. Created by automotive writer Brock Yates in 1971, the secret event was an invitation-only challenge to see who could drive from New York City to Redondo Beach, California, in as quick of an elapsed time as possible. Cars left at one-minute intervals from the Red Ball Garage in Manhattan. Many of them never made it to the finish line, or without a serious encounter with law enforcement.
RPM felt his Shelby had the basics required to compete in such an event but that it would also need a lot of modification in order to maximize its potential. He approached the challenge with the philosophy it is far better to drive fast, safe, and under the radar than it is merely to drive fast. Not only would each delay by law enforcement cost you valuable time and money, but getting busted for a high-speed infraction would probably land you in jail. And, with the national speed limit being 55 mph, the Shelby could bust through that in about five seconds.
“Asked why he decided to build-up his show-winning Shelby instead of some other car, RPM answered “It wasn’t a numbers-matching car, so it didn’t bother me to modify it. I wouldn’t have done all this to a numbers-correct vehicle.”
His goal was to keep the exterior of the Shelby as stock-appearing as possible, while under the skin building up an intricate system of high-tech electronic devices and mechanical systems to give him an advantage in dealing with each challenge of driving long distances at high speeds.
A little background: RPM worked for a company that built high-voltage power stations and cross-country transmission lines — also known as “The Power Grid.” His knowledge of electrical and mechanical engineering helped him in designing many of his Shelby’s one-of-a-kind components. A trusted friend (an aerospace engineer) provided valuable guidance on the microwave countermeasures, such as the “Radar Communicator” that causes a radar gun’s readout to show “55 mph” regardless of the Shelby’s speed.
About 20 percent of a strategy to win a cross-country race is to drive fast. The other 80 percent is made up of important things such as cruising range, vehicle reliability, driver comfort, vehicle stealth, and safety. RPM’s first order of business was to upgrade the car’s brakes, adapting a pair of ’67 Shelby four-piston calipers and rotors to the rear axle. Remember, this was in 1979, and there were no conversion kits for such a swap. No aftermarket setups with giant rotors and race pads. Just junkyards to hunt through, for donor cars.
Next on the list was increasing the car’s cruising range. The stock 15-gallon Mustang fuel tank was good for maybe 100 miles at Cannonball speeds, so RPM removed the Shelby’s rear seat and constructed a 47-gallon auxiliary tank out of aluminum in its place.
He then swapped the stock 3.50 rear gears for a 2.47 ring-and-pinion and chucked the existing four-speed for a Doug Nash five-speed gearbox.
With the stock Shelby 15×7-inch, 10-spoke aluminum wheels and Goodyear NCT radials, sized 245/60×15 — there were NO 16-inch or larger passenger car wheels/tires in 1979 — the new ultra-tall rear-end gearing and electronically-tunable dual Holley 600 carbs improved the highway fuel economy to nearly 19 mpg at cruising speeds, and gave the car a usable range of about 1,100 miles.
Every gasoline stop he was able to eliminate, by further improving the car’s highway fuel economy, saved around 15 minutes of down time (the elapsed time between when you drop below cruising speed to exit the highway, plus the time to get the fuel and pay, and the time it takes until you’re back up to speed.) Fifteen minutes at 120 mph equals 30 miles.
The car’s headlights were the next area of modification. RPM fitted a pair of aircraft landing lights under the bumper, and devised a cockpit-adjustable electric control to move the lights up/down and side-to-side, for targeted illumination. Of course, many new cars today have a similar system of “adaptive headlights” that turn in the direction of a corner, but, in 1979, RPM had the only one.
Further tricking out the forward lighting, RPM affixed infra-red lenses to the lights and located a pair of military-spec night vision goggles for the driver and passenger to wear. The resultant “dark running” ability proved valuable on vulnerable stretches of highway where it felt better to slip through completely undetected.
Just about every electrical device, moving part and fluid in the car is being monitored, measured, and cooled when necessary. The bevy of switches in the aluminum center console control the six-stage headlights, taillight cutouts, and oil feed into the engine from a nine-quart reserve tank, while driving. Aircraft landing lights were modified by RPM to adjust up/down and side-to-side from the cockpit. Infra-red lenses can be placed over the headlights for “dark running.”
When RPM handed me the night vision goggles, he hadn’t told me about the infra-red lights. We were running out of Rifle, Colorado, on a test trip across parts of the High Plains to the Wyoming border and back. When he hit the IR light switch, and the outside world went black, my first experience peering through night vision glasses was surreal. (For safety reasons, RPM only used IR-mode when no other vehicles were in the vicinity.)
Reliability over long distances, in all types of weather, was next on RPM’s list. Virtually every fluid in the car was being monitored, measured, and cooled when necessary. The 428’s 10-quart oil pan was augmented by a 9-quart oil reserve with sensing unit and automatic feed capabilities, should the engine need more oil while running. There are temperature sensors for the brake pads, wheel bearings, and fuel entering the carbs. Everything but how many calories you’re burning is being monitored by something.
Another feature ahead of its time was RPM’s unique design of electrically-opening headers. By modifying an electric motor to a geared screw-drive, 12-volts could be switched on to open a collector plate in the exhaust system. In 10 seconds, the exhaust went from stock Shelby Mustang in tone to full race car tenor. Flip the switch the other way, and the screw-drive closed the plate tight.
The interior of the Shelby retained its stock dashboard, steering wheel, door panels, and rollbar, but had been modified with Recaro seats and a bevy of devices for radar detection. Specially built aluminum overhead and center consoles contained the switch-gear, gauges, and controls for the vehicle’s many mechanical and electronic systems.
On the road, the ride quality was comfortable enough to allow for co-driver naps between stints behind the wheel, which becomes ever more important as the hours wear on, and you still have 2,500 miles to travel. Acceleration from the 428 was surprisingly stout, even above 80 mph, given the long-legged rear gearing. RPM liked to keep the 15-gallon stock tank filled with racing fuel, “just in case.”
As fate would have it, 1979 was the last of the “officially unofficial” Cannonball events, so RPM did not get his Shelby built in time to run in one of those. But, he did compete in the similar-themed “U.S. Express,” as well as the “Four Ball Rally” (with this author, in the ex-California Highway Patrol car we’d sell to Dan Aykroyd after the event) and in two of the later legal and sanctioned “One Lap of America” 7,500-mile seven-day ultra-endurance events.
During all of those long days and seemingly-unending miles of driving, RPM’s Shelby was 100 percent reliable, and neither he nor his co-drivers were ever stopped by law enforcement. That’s a lot of miles, at a lot of speed, in a lot of weather, to have such a perfect outcome.
In 1985, RPM brought his car to the Popular Hot Rodding offices in Los Angeles. We arranged for him to show it to Carroll Shelby at the Chrysler-Shelby Development Center in Santa Fe Springs, California. Yeah, back when Shel’ was building Dodges. Carroll crawled into the cockpit of the GT500, looked at all the modifications, listened to the stories, and then said, “RPM, you’re one crazy sumbitch. But I love it!”
When we last saw RPM’s special Shelby, it was in 1987. Then, the car disappeared. It went off the grid for nearly 30 years. Until recently, when RPM contacted me and asked if I‘d like to get reacquainted with the GT500.
Looking at the exterior of the car today, not much has changed since we last saw it. Under the skin, however, RPM has given the Shelby some new muscles and increased its high speed performance even more. The 428 has been replaced by a 427 side-oiler, stroked to 483 cubes. Dove aluminum heads cover 10.85:1 compression pistons, and valve actuation is via a Lunati solid-lifter cam, Milodon gear drive, and Shelby stainless steel roller rockers. Oil capacity has been upped to a 12-quart pan, but retains the 9-quart reservoir with automatic transfer capability.
Buried underneath a custom-fabbed aluminum cold-air plenum that seals to the hood is a Shelby medium-riser intake housing twin Holleys. Venting radiated engine and exhaust heat out through the aftermarket Shelby fiberglass hood (with rear gills) are six small but efficient electric fans that each pump 180 cfm away from the engine compartment.
Backing up the powerplant is a Richmond 6-speed that replaces the Doug Nash 5-gear and gives the car an overall top gear ratio of 1.95. That lets the GT500 loaf along at a mere 2,000 rpm at 70 mph (4,000 rpm at 140 mph) and delivers an “estimated” top speed of close to 180 mph. However, knowing RPM’s penchant for under-promising and over-delivering, “estimated” probably means “observed.”
Factor in the undisclosed number of high-speed long-distance runs that RPM made on his own, in an effort to best his previous elapsed times, and his legend will never be fully known, even by his closest friends. But, most importantly, he always achieved his main goal of arriving home safe, secure, and undetected. The perfect stealth mission.
Our personal connection to this car goes back to 1982. RPM called the Popular Hot Rodding offices, and I answered. The deep resonant voice on the other end of the phone listed off more than 20 unique modifications he’d made to the car — many that he designed and built himself. Frankly, the car sounded too incredible to be true. We had to see it for ourselves. I flew to the Midwest location where we’d agreed to meet. And, as I soon discovered, everything RPM had told us was true. And more.