The Plymouth Road Runner is a mid-size car with a focus on performance built by Plymouth in the United States between 1968 and 1980. By 1968, some of the original muscle cars were moving away from their roots as relatively cheap, fast cars as they gained features and increased in price. Plymouth developed the Road Runner to market a lower priced, basic trim model to its upscale GTX.
Second generation (1971–1974)
1971
In 1971, the coupe bodywork was completely changed to a more rounded "fuselage" design in keeping with then-current Chrysler styling trends, including a steeply raked windshield, hidden cowl, and deeply inset grille and headlights. In a departure from previous thinking, the B-Body two-door bodies shared little if any sheet metal, glass, or trim with the four-door bodies. The convertible was canceled. The interiors could be ordered with 6-way power leather seats, thick deep-pile carpeting, and additional sound-proofing was installed. A/C, and power steering could be had, except on the Hemi. 1971 was a high-water year for ride and handling for the Road Runner. The overall length was increased, but the wheelbase was shortened an inch. It also saw the introduction of the 340 4-BBL option, and a detuned 383 "Road Runner" engine with 8.7:1 compression, and power dropping to 300 hp (224 kW). In return, Road Runners with the 340 and 383 engine received a standard insurance rating without the costly premiums normally tacked onto muscle cars. The 383 would now run on regular gas.The 440+6 and 426 Hemi were available, though this would be the last year for them. The tall axle ratios with the 8 3/4" Chrysler and Dana 60 rear ends, as well as the wide and close ratio 4-speed transmissions could be had with any of the engine choices, though few cars were built with the six-pack or Hemi engines. Aerodynamics were much improved over the first generation Road Runners, resulting in much-improved high-speed handling.
1972
1972 saw new emission regulations drive power down and 1/4 mile times up.
The 1972 model was nearly identical to the 1971 with a few minor changes. The grille design was cleaned up, and the tail lights were changed to match the new aerodynamic look of the grille. Side marker lights changed from the flush mounted side markers to the surface-mounted units that were adopted across the entire Chrysler line-up for the 1972 model year. The optional bumper guards for 1972 included a rubber strip surrounding the tail lights and a rubber strip below the grille. The big differences came in the cutting back of performance options for the car. The suspension, rear axle ratios (a 3:55 ratio was the tallest available), and most noticeably the engines changed, with the big-block 383 being replaced by a larger-bore (and lower performance) 400 CID version as the standard engine. The small-block 340 CID as well as the performance version of the 440 CID engine (with a 4-barrel carburetor, performance camshaft, and dual exhausts) were also available, and for the last time a 4-speed manual transmission could be paired with any of the three engines. All of the engines suffered a drop in compression ratios to allow use of low-lead/no-lead gas and to meet the first round of emissions regulations. The 280 hp (209 kW) 440 engine was the basis for the Road Runner GTX (the GTX was no longer a separate model) and was available on Road Runners from 1972 to 1974. The 1971-72 Road Runner sheetmetal was used by several NASCAR racing teams for their racecars and ran well on the circuit during the 1971-74 seasons. Richard Petty won the championship both in 1971 and 1972 using the Road Runner-based cars, winning 30 races over the two seasons.
For 1972 power ratings on all engines looked much lower on paper due to the new SAE net measurement system. The famed 426 Hemi was discontinued for 1972, and only five 440 Six Barrel equipped cars were produced before this engine option was dropped (it was determined the 440 six-pack could not meet the stricter 1972 emissions regulations) in the fall of 1971.
1973-1974
The 1973-74 models received completely new sheet metal and had more conventional squared-up front-end styling and changes to the rear that more closely resembled the four-door models than the 71-72s. In addition, the interior options included retaining power seats and windows as well as offering plusher carpeting and seat covers, moving the car to a slightly higher level of luxury. The restyling helped sales which were up 40% over the 1972 models. In testing 1/4 mile times were getting close to the 16s, top speeds had dropped to barely over 125 mph (201 km/h), and the car moved further away from "musclecar" status. The base engine for the 1973-74 models had dropped down to Chrysler's workaday 318 CID V8 but equipped with dual exhausts which bumped the power up to 170 hp (127 kW). After 1972, no 440 with four-speed manual cars were built. The code E68 400 cu in 260 hp engine was the biggest Plymouth offered with the 4-speed, which could also be had with the 340 (1973), and 360 (1974) engines. The 318 was equipped with a 3-speed manual transmission as standard (though very few were built), and the TorqueFlite as an option, though at least one 318 engine 1974 car was built with the 4-speed manual transmission equipped with a Hurst shifter. The 440 cu in engine, boasting 280 hp was still available for 1973 and 1974, but only mated to the 727 TorqueFlite automatic, with 3.55 sure-grip 8 3/4 rear axle gearing available. (Some info from the Dodge and Plymouth Muscle Car Red Book, by Motorbooks International.)
Source: Wikipedia
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