What engine was standard in the 1968 Plymouth Road Runner?

The standard engine in the 1968 Plymouth Road Runner was the 383 cubic inch V8.

Plymouth built the Road Runner as a relatively affordable, stripped-down muscle car based on the Belvedere. Its 383-cubic-inch B-series V8 used a four-barrel Carter carburetor and was advertised at 335 horsepower, helping the lightweight coupe deliver serious performance without the price of a Hemi.

The 426 Hemi was available, but it was an expensive option rather than the standard engine. The 440 was also associated with Chrysler’s larger performance cars and later Road Runner variants, which can cause confusion. The standard 383’s special Road Runner tune included a performance camshaft and increased compression; cars ordered with air conditioning received a lower-rated 330-horsepower version because the hotter cam produced insufficient vacuum for the system.

The 1968 Road Runner also came with a four-speed manual transmission as standard equipment, while Chrysler’s three-speed TorqueFlite automatic was optional. Plymouth expected about 20,000 sales but sold roughly 45,000 in the first year.