1970 Plymouth Road Runner - Worth The Wait

Paul Gaspard had to hold off several decades to build the Mopar of his dreams, but this 600hp Road Runner was worth it

The coyotes smell blood. There's an orange 1970 Plymouth Road Runner on the loose, and man does it look tasty. With 31 inches of rear contact patch in total, hookin' and bookin' shouldn't be an issue. As Paul Gaspard cracks open the secondaries from a Third gear roll, however, the Road Runner's 561 lb-ft of rear-wheel torque pulverize the Hoosier radials into oblivion. That's 500 ci of big-block Mopar for you, baby. Like the experienced hooligan he is, Paul eases up on the throttle just a bit as the B-Body surges past triple-digit speeds. Those coyotes must be driving Chevys and Fords, because they're nowhere in sight. Although Paul didn't get to experience the muscle car heyday on U.S. soil back in 1970, he's been making up for it by building one cool Mopar after the next for the past 40 years.

Brand loyalty is an emotional connection that's often handed down from generation to generation, but for Paul his love of Mopars has always been based on pragmatism. He worked as an auto mechanic during his first four years in the Air Force, and that's when he noticed something peculiar. "I got to work on all kinds of cars, but it seemed like I was fixing Fords and Chevys all the time while the Mopars never broke down. My work truck was a Dodge utility van with a 318 small-block and a four-speed trans, and that truck really turned me on to the Mopar stuff," he fondly recalls. "No matter what, that Dodge truck just ran and ran and ran. The Mopars were always so much easier to maintain and keep running. I got stationed in Germany from 1969 to 1970, so I missed the heyday of muscle cars. Most of the GIs brought Chevys overseas, so I didn't get to see most of the cool Mopars of the time. All my friends had Camaros and Corvettes, but my passion for Mopars lived on."

"The Road Runner was in absolutely terrible condition. It had no floors or trunk pan, and the quarter-panels and package tray were completely gone." —Paul Gaspard

Once back on U.S. soil, Paul got himself a new '74 Dodge pickup with a 318. Although the yearning to build a proper muscle car raged inside, the life of a serviceman presented its challenges. "Being in the military meant that we had to move around all the time, so that made it tough to haul around my play toys, however, I insisted on buying Mopars even as daily drivers, and, in fact, our family has only bought two non-Chrysler vehicles to this day," he says. Once he was able to set down some permanent roots, Paul picked up a '73 Challenger in 1989. It was a 340-powered machine with an automatic that he used as a daily driver until it hit 250,000 miles. He eventually sold it to his son, Josh. The duo built every last component on the car together, including the bodywork, and it now runs 10-second e.t.'s at the track where it's bracket raced just about every weekend. Needing another project of his own, Paul picked up a '69 Barracuda in 1994. After swapping in a 440 big-block and enjoying it for several years, a certain B-Body caught his eye.

2/17

Having spotted a '70 Road Runner for sale for $1,900, Paul couldn't pass it up. He sold the Barracuda to help pay for it, but after bringing it home he quickly realized how much work it needed. "The Road Runner was in absolutely terrible condition. It had no floors or trunk pan, and the quarter-panels and package tray were completely gone," Paul explains. "Fortunately, the frame wasn't damaged, but there was rust everywhere. The car basically needed all new metal from the doors rearward. I got in a routine for working eight hours a day, eating a quick dinner, and then working on the car in the shop each night for a couple of hours."

As the metalwork neared completion, Paul began pondering the direction of the build. He knew a stock restoration wouldn't be sufficiently exciting for his needs, but he didn't want to take away from the Road Runner's unique character, either. "I wanted to keep the car close to stock appearance wise, but at the same time I wanted to upgrade every single part in it. I wanted to option the car out like I would have in 1970 if I had the opportunity to purchase the car brand new," he says. The result is a street/strip B-Body that's a bit restomod and a bit Pro Street without going over the top in either direction. Sure, it has monster 29x15.5 rear meats, but the stance is raked just enough to look aggressive yet not garish. Yes, the 500ci big-block packs some serious punch, but it idles smoothly and doesn't require a big ugly scoop.
Speaking of engines, Paul's learned a thing or two about building them over the years. He's got at least a half-dozen motors in various states of assembly at any given time at his home shop. If there's a Mopar buddy in need, he's always willing to leverage his experience to hook them up with one of his proven engine combos. Not surprisingly, his big-block is a no-nonsense combination that flat-out gets the job done. Even with an Edelbrock high-rise intake manifold, the Road Runner's 500ci setup fits beneath the stock hood with room to spare. That's because Paul knew that a B-series 400 block had plenty of extra bore and stroke capacity left in it, and a taller RB block wasn't necessary. He started with a stock iron block, bored it to 4.3750 inches, then fitted it with an Eagle 4.150-inch steel crank and rods. Diamond forged pistons provide an 11.4:1 squish ratio, which goes a long way in taming the Hughes 236/242-at-.050 hydraulic roller camshaft. Ported Edelbrock Performer RPM aluminum castings with 2.140/1.880-inch valves provide the air supply, while a Demon 840-cfm carburetor atomizes the fuel. At wide-open throttle, the big-block Chrysler sounds oh-so sweet thanks to a set of TTI long-tube headers, a custom H-pipe, and dual 3-inch DynoMax mufflers.

3/17 What looks like a ho-hum 383 packs 500 ci and 600 hp. Why don’t more people build them this way?

With the exception of the machine work, Paul designed and assembled the entire combination himself. A testament to his experience and good work, the big-block lays down 498 hp and 561 lb-ft of torque on the chassis dyno. With power like that in a low-deck Wedge motor, who needs a Hemi? "If you're going to stay with an old Wedge motor, a stroker is the only way to go. They make tremendous torque, which is great for a big heavy car like this," Paul explains. "You can make lots of power with a small-block, but you have to turn them hard to get them out of the hole. The knowledge I gained from building different types of motors came in handy when I put this 500 together. Although you can bore a 400 block out to 4.380 inches, I kept it at 4.3750 inches to aid with the cooling. Now the car only runs 190 degrees during a Texas summer day."

If you haven't figured it out by now, Paul needs a bit more excitement than the typical retiree. That's why there's a pistol grip shifter hooked up to a Tremec TKO 600 five-speed manual between the front seats. We can assure you that Paul's dropped the lever down to Third and let the big Wedge eat on many occasions. Given the engine's epic torque output and the driveline shock imparted by the row-it-yourself tranny, Paul didn't take any chances with the rearend and opted for a Dana 60. It has been beefed up with Moser 35-spline axles and a limited-slip differential. As Paul was more than happy to demonstrate during our testdrive, the car pulls hard in high gear, despite the freeway-friendly 3.73:1 ring-and-pinion set.
As with the rest of the car, Paul kept things simple on the chassis side of the equation while still upping the performance ante. The front and rear suspension were completely rebuilt with new bushings and Monroe shocks, then enhanced with a 1-inch front sway bar and Calvert Racing leaf springs and traction bars. Paul tubbed the Road Runner himself to make room for the 15.5-inch tires, and cut and narrowed the Dana 60 rearend as well. Bringing the hefty B-Body to a halt in a hurry are four-piston Wilwood disc brakes at every corner, and Hoosier radials wrapped around 15-inch Weld Pro Star wheels do their best to keep everything glued to the pavement.

4/17 Although a beefed-up 8.75-inch rearend would probably have held up fine, opting for a Dana 60 gave Paul some extra assurance. The Road Runner’s 29x15.5 tires are a throwback to the glory days of Pro Street, and gives the car the perfect amount of rake.

After putting the finishing touches on a three-year build, Paul had to let it rip at the track just to see what the Road Runner could do. The car promptly snapped the driveshaft upon dumping the clutch for the first time on slicks. In order to avoid a similar fate the next time around, Paul ran the car on radials. This netted tons of wheelspin en route to a 12.60-second pass at 116 mph on a lethargic 2.18-second 60-foot time. If the Road Runner put the power down more efficiently, it could easily run over 120 mph through the traps, which is very impressive considering its voluptuous 3,635 pounds of mass.

It may seem like Paul is having too much fun in his Road Runner, but this is a man who has paid his dues. Pretending to like Chevys during all those years he was stationed overseas has paid off, and perhaps he's merely being rewarded for his sportsmanship. Either way, any coyote hoping to chase this Road Runner better leave the Chevy at home and bring a Mopar.
Fast Facts
1970 Plymouth Road Runner
Car owner: Paul Gaspard, 63 • Marion, TX
Engine
Type: Chrysler 500ci big-block
Block: factory 400 block, bored to 4.375 inches
Oiling: Melling oil pump, Milodon pan
Rotating assembly: Eagle 4.150-inch steel crank and H-beam rods; Diamond 11.4:1 forged pistons
Cylinder heads: ported Edelbrock Performer RPM aluminum castings with 2.140-/1.880-inch valves and 84cc combustion chambers
Camshaft: Hughes 236/242-at-.050 hydraulic roller; .520-/.525-inch lift; 108-degree LSA
Valvetrain: COMP Cams valvesprings, retainers, pushrods, and timing set
Induction: Edelbrock Victor intake manifold, Barry Grant 840cfm carburetor
Ignition: MSD billet distributor, coil, and Digital 6 ignition box
Exhaust: TTI long-tube headers, custom H-pipe, dual 3-inch DynoMax mufflers
Cooling system: Mopar Performance water pump, Be Cool radiator, SPAL electric fans
Output: 498 hp and 561 lb-ft at the rear wheels
Built by: owner

Drivetrain
Transmission: Tremec TKO 600 five-speed manual; McLeod aluminum flywheel and clutch
Rear axle: Dana 60 rearend with 35-spline Moser axles, 3.73:1 gears, and limited-slip differential

Chassis
Front suspension: rebuilt stock with 1-inch factory sway bar and Monroe shocks
Rear suspension: Calvert Racing leaf springs and traction bars; Monroe shocks
Brakes: Wilwood four-piston discs front and rear
Wheels & Tires
Wheels: Weld Racing Pro Star 15x8, front; 15x12, rear
Tires: Hoosier 28x9.5x15 Pro Street radials, front; 29x15.5x15, rear

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