1968 Plymouth Road Runner

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Plymouth Road Runner

Plymouth Road-Runner

383 CID / 6.3 Litre
335bhp (250 kW)
4 spd. man / 3 spd. auto
Top Speed:
n/a (but very fast)
Number Built:
5 star
Plymouth Road-Runner
Reviewed by Unique Cars and Parts
Our Rating: 5

The Most Honest Muscle Car Ever Made

Paying $50,000 to Warner Brothers to use the name and likeness of their Road Runner cartoon character (as well as a "beep, beep" horn, which Plymouth paid $10,000 to develop), the Road Runner was the simplest, starkest, most brazenly pure, non-compromising super car in history. But it was this very simplicity that American muscle car aficionados would soon realise was very much a virtue. By 1968 the super cars had been around for nearly eight years, but the ’68 Road Runner was one of the first that had really come of age. For those not in the know, the Road Runner was based on Plymouths lowest-priced Belvedere body, and represented a simple ethos in muscle car design.

But, muscle cost money, and rather than sacrifice performance for a cheap compromise, Plymouth decided to incorporate whatever quality was necessary and let the price fall where it may. For this reason, the car was more expensive thatn many would have expected at release; but at least they were satisfied physically. Perhaps one of the wisest decisions from Pontiac for the ’68 model year was to replace the old 2-door Belvedere with what had developed into the then best looking low-priced body in the USA.

By slicing off some of the box top and sticking in some flip-out CT-type rear quarter windows, the coupe came away with a sporty appearance that had long been undeserved by Detroit. The old Plymouth 383 4-bbl. V8 was strong and durable, but it hardly established new plateaus of performance for its size. But it was obvious that the unit reeked with potential. Plymouth's modifications to the '68 version were so effective that most road testers did not believe it was the same engine. The deflowered powerplant was unique to the Road Runner, so no compromises had to be made for more delicate personalities.

The Plymouth engineers started by ensuring the 383 could breathe properly, by fitting the engine with the same cylinder heads, crankcase windage tray, intake manifold and camshaft as the 440-cu.-in. engine. The performance peaks for the 383 were high on the rev scale - 5200 for hp and 3400 for maximum torque of 425 lbs. ft. - which gave it plenty of flexibility for controlled handling on tight roads, plus long-legged sprints between shifts. Its extra 5 horsepower rating was the result of using the radical cam from the 440 Super Commando and a .25 raise in compression to 10.5:1 (vs. 10.25:1 with the 330 horsepower 383).

When air-conditioning was ordered, the cars received the 330 h.p. version, as the radical cam specs of the 335 h.p. version didn't create enough vacuum to accommodate a/c ; and there were concerns of overrevving which would grenade the RV-2 York compressor. For an extra $714, Plymouth would install a 426 CID Hemi rated at 425 bhp (317 kW) and 490 lb·ft (664 N·m) of torque. Combined with low weight, the 6-passenger Road Runner could run the 1/4 mile in 13.5 seconds at 105 mph (169 km/h). It would prove to be one of the best engines of the muscle car era, and the Road Runner one of the best platforms to utilize it.

The standard equipment transmission was a four-speed manual with floor shifter, and like the Charger R/T, you could option Chrysler's three-speed TorqueFlite automatic. Early four-speed '68 Road Runners featured Inland shifters, which were replaced by the more precise Hurst shifters during the course of the model year. The Road Runner usually ran with a 3.55:1 axle ratio and SureGrip differential – which was pretty much a necessity if you wanted to lay down good times. Yet, even with the SureGrip and F70 x 14 tyres, many found it easy enough to induce wheel-spin. It was a car that would eclipse 100 mph in the quarter without difficulty, and without the 4-speed manual transmission.

On the Road

The Road Runner was a good handler, but it was not perfect. The main limitation were the settings on the rear springs, which some performance minded owners claimed was about one half of a spring in the rear suspension from nearly ideal. The car did deserve kudos for having the maximum of "production" suspension modifications: 6-leaf springs with seven plastic inter-liners on the left rear, five full leaves with two half leaves and six plastic inter-liners at the right rear; .92-inch diameter, 41-inch long torsion bars, heavy-duty shocks and a front anti-sway bar. But the car needed more springing at the rear and more camber in front. Under heavy lock and pressured negotiations, the size of the engine made itself known and stubbornly resisted the inertial alterations you might wish to impose.

There was lots of body roll and you began to love those wide tyres for their integrity under the assault of all that weight, but they held well and the rear end stayed where it was supposed to. Stripped as it may be - about 50 pounds less than its sibling GTX and a couple of hundred pounds less than many of its peers - the Road Runner still packed 3660 pounds of meat without the driver and with the tank topped. And with a 116-inch wheel-base carrying a 202.7-inch moment of force above it, you needed to have your wits about you when pushing the car 10/10ths. That said, the Road Runner package would keep you out of more trouble than most other muscle cars of the ‘60s.

Power steering, usually an undesirable element for performance machines, had also become a necessary and recommended addition, not only because it subdued the inherently ill-handling brutes, but also because the steering ratios made the cars much more nimble. In the case of the Road Runner, it was lowered from an unwieldy 28.8:1 manual ratio to 18.8:1 with power - 3.5 turns lock-to-lock - very good figures for a "sedan."

And even though the car was lighter than its competitors, Plymouth had somehow managed to prevent "feel" from diminishing completely at road speeds. Much of this quality was a result of the wide tyres, but it was, nevertheless, a major plus-factor for the Road Runner. Where the suspension had its limitations, the brakes compensated impressively, the 4-wheel drum brakes able to pull the Road Runner up in 126 feet with no steering correction. Of course, they were 11 inches in diameter both front and rear, but, as good as the drum brakes were, the wise ticked the 11-inch front disc option box..

Behind the Wheel

The Road Runner's interior was "Spartan," but deliberately so, and that's what gave it a favourable quality. It was meant to be, and this was the first muscle car in which it looked good. As a matter of fact, if it weren't "Spartan," it would have looked like a wannabe. Arguably the Road Runner’s greatest virtue was that it was basic and honest – it was not trying hard to be something it wasn’t. It was expensive, it was black, it was tough, it had lots of vinyl, and that vinyl was gray and hard. Plymouth hadn't prostituted the Road Runner to the fabric industry; the inside of the car, as stark as it may have been, conveyed an overall feeling of quality because of well dampened noise.

Early model Road Runners even lacked carpets, and only a few options were available - just the basics such as the aforementioned power steering and front disc brakes, AM radio, air-conditioning (except with the 426 Hemi) and automatic transmission. A floor-mounted shifter (for the four-speed) featured only a rubber boot and no console so that a bench seat could be used. The earliest of the 1968 models were available only as 2-door pillared coupes (with a B-pillar between the front and rear windows), but later in the model year a 2-door "hardtop" model (sans pillar) was offered.

But Plymouth did provide options for the posers. For our money, a simple black version would have done just fine. But there were those that needed their car to look as fast as it was. You could option bird decals on the sides and back of the car, a huge flat black paint patch on the hood, 1/8-inch wide paint stripe on the body, and various (ridiculous) chrome panels. Some insignificant details would be annoying to an unreasonable perfectionist, such as tail light wires inside the trunk that could be vulnerable to suitcases, and those frustrating knurled knobs for panel lights, but the net result was the most honest muscle car ever made. Brilliant.

Plymouth expected to sell about 2,000 units in 1968; actual sales numbered around 45,000. This placed the Road Runner third in sales among muscle cars with only the Pontiac GTO and Chevy's SS-396 Chevelle outselling it. Dodge debuted the Road Runner's cousin, the Super Bee, as a mid-1968 offering after seeing Plymouth's success with the Road Runner, along with demands from Dodge dealers for their own low-priced muscle car as the Dodge Boys started the model year with the higher-priced Charger R/T and Coronet R/T - both of which were priced similar or higher than the Plymouth GTX.
1968 Plymouth Road Runner
1968 Plymouth Road Runner

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Plymouth Car Commercials
The History of Plymouth (USA Edition)
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