1970 Plymouth RoadRunner 440 6 pack
1970 brought new front and rear end looks to the basic 1968 body, and it would prove to be another success. Updates included a new grille, leather seats, hood, front fenders, quarter panels, single-piston Kelsey-Hayes disc brakes (improved from the rather small-rotor Bendix 4 piston calipers of '68 - '69 ), and even non-functional scoops in the rear quarters. The design and functionality of the Air Grabber option was changed this year to increase both efficiency and the "intimidation factor". A switch below the dash actuated a vacuum servo to slowly raise the forward-facing scoop, exposing shark-like teeth on either side. "High Impact" colors, with names like In-Violet, Moulin Rouge, and Vitamin C, were options available for that year. The 1970 Road Runner and GTX continued to be attractive and popular cars. The engine lineup was left unchanged although a heavy-duty three-speed manual became the standard transmission, relegating the four-speed to the option list along with the TorqueFlite automatic. This was to be the second and last year of the Road Runner convertible, with only 834 made. These cars are considered more valuable than the 1969 version due to a better dash, high impact colors and more options including the new high-back bucket seats shared with other Chrysler products which featured built-in headrests.
The relatively popular 440 Six Barrel was relegated to option status for 1970. The 1969 "M" Code Edelbrock aluminum intake was replaced by a factory-produced cast iron piece; however, due to a porous casting, there was a recall early in the iron intake-equipped 440+6 run, and these were supposed to be replaced with the more-desirable Edelbrock intake from the year prior.
Sales of the '70 Road Runner dropped by more than 50 percent over the previous year to around 41,000 units (about 1,000 ahead of Pontiac's GTO but still about 13,000 units behind Chevy's Chevelle SS-396/454). This would also be the last year of the road runner convertible with 834 total production. Only 3 hemi (R) code road runner convertibles were built. The declining sales of Road Runner and other muscle cars were the result of a move by insurance companies to add surcharges for muscle car policies - making insurance premiums for high-performance vehicles a very expensive proposition. Also, Plymouth introduced another bargain-basement muscle car for 1970, the compact Duster 340 which was powered by a 275-horsepower 340 Magnum V8 which in the lighter-weight compact A-body could perform as well if not better than a 383 Road Runner. Furthermore, the Duster 340 was priced even lower than the Road Runner and its smaller engine qualified it for much lower insurance rates.
The Chevy engine comment was a joke.