This 1968 Roadrunner Has The Heart Of A Viper!

A situation many automotive enthusiasts sometimes find themselves in revolves around an uncomfortable situation –inheritence…No, we’re not talking about fighting with your siblings over mom and dad’s prized old Buick. But rather, what to do with a car once you’ve already inherited it. Not so much from a logistical perspective, as from a dutiful steward sort of thing.

Ken Matlock’s 1968 Plymouth Roadrunner has gone through many changes since he inherited it from his father who owned it since new…The most notable of which is the monster supercharged HEMI under the hood.

If the inherited vehicle is in pieces or in bad shape, then the mission is simple – some sort of restoration is the name of the game. Getting it back on the road and whatnot…But there’s another example that seems more pertinent in the case of the electric green Roadrunner you see here. A car that’s been in the same family since it was new. A car that was already in decent shape when inherited.

So, what do you do with an inherited vehicle that is already in excellent running and driving condition? We know, you smart Alec’s in the room have already answered – drive it! But what if you love to modify your rides? Do you owe it to the previous owner to preserve the vehicle exactly the way they had it? Would it detract from their memory if you were to modify it? Should you take into account their taste over your own?

Daily Driven For Decades

Stance maketh the car…

Well, we’ve been in that very same situation more than once. It’s not a decision we take lightly, but one that should probably be handled on a case-by-case basis. For Ken Matlock, the choice was simple…

If you gotta baby it, you didn’t build it right.- Ken Matlock

“My old man bought it new, he built the 1968 Roadrunner a one-car garage. Now, it’s on a second-gen Viper chassis. I narrowed the rear end 12-inches, narrowed the front 4-inches, stretched the chassis, obviously, and performed lots of body modifications. It’s got a custom hood I built. It’s got a gen-three Hemi from Steve Morris. It made 1,115 horsepower on pump gas. It shifts with a G force 6-speed transmission, and it’s got all Mark Williams half shafts and driveshaft. It’s built to beat on – I don’t baby it. If you gotta baby it, you didn’t build it right.”

“I’m an ’80s baby and it’s been in the family since ’68, so he daily drove it until about 2002. It was pretty rough when I got it, and it took about six and a half years to build it. It was a labor of love and hate at the same time.”

How do you improve upon the venerable Roadrunner design? Mash it up with the equally notorious Dodge Viper.

While the green is impeccable, Matlock told us, this is not the first color it’s been…obviously. “Originally, it was gold, and then it was white, and then it was yellow, a real light yellow…and now this.”

Matlock also tells us, this is not the first iteration of his build. It has worn several colors of paint and has been powered by multiple powerplants. “I had a stroker motor, twin-turbo V10 in it for a while, but it was just super problematic ignition-wise. I was too cheap to buy a Motec so I pulled it out and put the Hemi in it. The driveability is way better, and the bottom end is way better. That v10 was a top-end motor…this one likes to party. She likes to blow ’em [the tires] off.”

Family Changes Things

We asked Matlock about when he took ownership of his green beast, what was the direction, because it’s a full-blown custom now…”I was young and stupid and the direction was…I wanted a standing mile monster. The car has got a full belly pan under it. It’s got a big diffuser in the back, all the wheel wells are vented to keep the pressure down, it’s got a 10-point moly cage, and it is 150 pounds heavy toward the rear on a 50/50 weight distribution.”

As if the monster Hemi didn’t sound good enough on its own, Ken decided to pipe the fumes out of a fender exit exhaust.

He continued, “We moved the motor and firewall back nine inches. Technically, it’s a modified mid-engine car, or so they called it, which means your crankshaft centerline is centered with your front axle. Whatever…It corners. The weight distribution is there and it’s set up right. It’s got an independent rear suspension and we narrowed that Viper rear by twelve-inches.”

“It’s also got parachute mounts and all that if I ever want to…but, life went on and I had a kid and then racing wasn’t a priority. So, I went past the whole racecar thing and it has yet to do the mile…I’m planning to do a half-mile, I’m just…I will do it! It will see the half-mile.”

After years of makeover time, the result is one imposing Roadrunner!

The custom hood incorporates more than just the Aerocatch hood pins, it also incorporates carbon fiber 2010 ACR viper vents grafted onto the original Roadrunner hood. “The whole front clip is glass and carbon fiber.” Although Matlock tells us, it isn’t exactly light, “The car is heavy – it weighs 4,200 pounds without me in it. But, I’ve got a lot of sound deadener in it and a big stereo. I’ve also got A/C and heat and it’s a four-passenger car.”

Powerplant

One of the things that immediately stuck out to us when Matlock popped the hood, besides the massive engine and blower combination, of course, was the cooling system. Matlock tells us, “In South Florida heat, the v10 was overheating like crazy, so I did this,” pointing to the massive heat exchanger for the Hemi’s supercharger. “It’s actually a radiator for a Jeep Grand Cherokee. The other one is a custom piece that’s got two pullers and two pushers. But, it’ll sit there until it runs out of gas with the A/C on, and that’s all I care about. I don’t have to worry about that!”

To cool the massive blown Hemi, Matlock had a radiator from a Jeep Grand Cherokee installed as the supercharger’s heat exchanger.

We moved on to the main attraction, the Hemi. We asked Matlock about the power numbers which he re-stated to be 1,115 horsepower on pump gas, of which Steve Morris has a video. When asked about the engine’s specific combination, Matlock replied, “Well, it’s a 426ci gen-3 Hemi with a 3.6L Kenne Bell supercharger on top. The engine made 1,115 horsepower at the crank. Backing the engine is a fully-built G-Force T56 Magnum six-speed with a twin-disc McLeod clutch and an SFI-rated bell housing. We’re only pushing 14 pounds of boost, but the rest is a Steve Morris secret. I believe it’s an 8.5:1 compression motor though…He likes to not tell you his formula, and I don’t blame him, that’s how he makes his money.”

The Kenne Bell blower sets off the top of the Hemi.

“I built it to drive it – it ain’t a quarter mile cruiser, you know what I mean?”

The beast of a Mopar has got three fuel pumps and a transfer pump that feeds into a surge tank, and the diffuser is actually the fuel tank. The fuel tank is the full width of the car and it goes from the bumper all the way to the rear end and it holds 34 gallons of gas. Matlock says, “I built it to drive it – it ain’t a quarter mile cruiser, you know what I mean?”

We feel sorry for those of you reading this at home who didn’t get to hear it in person because this thing’s got an incredible chop at idle. Ken told us, “The mufflers are actually in front of the firewall, and they wrap and dump out of the fenders. When I had a twin-turbo setup it was just run to the turbo and then out the door – no mufflers, and actually, Magnaflow sponsored me with all that.”

Interior

The interior features a leather-wrapped ten-point Chromoly cage, bucket seats, and he brought the whole family so the tradition his father started 50 some odd years ago continues… the interior is replete with the iconic pistol-grip shifter, two big screens, one for entertainment, and one that manages the Holley EFI system.

Air conditioning and all the creature comforts someone could ask for.

Matlock tells us, “It’s crazy, but this white stuff on the gas pedal is from when my father used to do concrete, and it was left after a job and I never cleaned it out when I put it back together.” We guess some things can remain even when you go full custom with your dad’s old ride. Matlock continues, “he drove it to work every day, so…”

Some things are just required in a big body Mopar, and a pistol grip shifter is one of them.

Exterior

The big body Mopar has a lot going on on the outside. Of course, your eye is drawn immediately to the color, the wheels, and the stance. But don’t be fooled, there are plenty of little nuanced parts to make note of. One of which is a factory Plymouth piece that we’ve always loved on the roadrunners – the curved back glass.

A full belly pan from front to back in preparation for high-speed half-mile and standing-mile driving.

Wheels And Tires

While Matlock explained how limited his options were when choosing the wheels for his Roadrunner because of the six-lug Viper pattern, we couldn’t help but guffaw over the 20×15 Nutech wheels wrapped with Mickey Thompson 29×18 tires. Ken tells us the company is no longer around.