1968 Plymouth Road Runner Engine Options and Specifications
In 1968 the Plymouth Road Runner could be ordered with two different high performance engine options.
For the 1968 Road Runner, the 383 High Performance 4 barrel engine was the standard engine. One engine option was available which was the 426 Hemi.
This article will include the 1968 Plymouth Road Runner engine options and their specifications. This includes the engine code, cost, displacement, horsepower, torque, compression ratio, camshaft, lifter type, valve sizes, bore, stroke, air cleaner, exhaust, fuel and carburetion.
1968 Plymouth Road Runner Engine Options and Specifications
The 1968 Road Runner was available with the following two engines.
- 383 High Performance 4-barrel (Standard)
- 426 Hemi (Optional)
1968 was the first year for the Road Runner, therefore there is no engine comparison from the previous year.
The Plymouth data book indicates air conditioning on a 4-speed was not available. Evidence indicates some Road Runners were produced with a 383, 4-speed and A/C. In these rare incidences, the 330 horsepower 383 4 barrel would have been used.
1968 Road Runner With a 383 High Performance 4-barrel
The 383 High Performance 4-barrel was available as the standard engine for the 1968 Road Runner.
This engine made 5 more horsepower (335 H.P.) than the other 383 4 barrels available in other Plymouths. It had the same camshaft as the 440 high performance engine.
The engine code was 62. Let’s take a look at the specifications.
| Specifications | 383 4-barrel |
| Displacement | 383 |
| Bore and Stroke | 4.25″ x 3.375″ |
| Horsepower | 335 @ 5,200 RPM |
| Torque | 425 @ 3,400 RPM |
| Compression Ratio | 10.0:1 |
| Camshaft | High lift, long duration, high overlap |
| Cam Duration/Overlap | 268°/284°/46° |
| Cam Lift | .450″/.458″ |
| Lifter Type | Hydraulic |
| Valve Diameter, Intake | 2.08″ |
| Valve Diameter, Exhaust | 1.74″ |
| Carburetion | Single Carter 4-bbl |
| Air Cleaner | Unsilenced |
| Exhaust System | Dual exhaust |
| Fuel Recommended | Premium |
1968 Road Runner with 4-speed and A/C (383 4-barrel)
As stated earlier, when a Road Runner was produced with a 4-speed and A/C it had the 330 horsepower engine.
The engine code was 62. Let’s take a look at the specifications.
| Specifications | 383 4-barrel |
| Displacement | 383 |
| Bore and Stroke | 4.25″ x 3.375″ |
| Horsepower | 330 @ 5,000 RPM |
| Torque | 425 @ 3,200 RPM |
| Compression Ratio | 10.0:1 |
| Cam Duration/Overlap | 256°/260°/32° |
| Cam Lift | .425″/.435″ |
| Lifter Type | Hydraulic |
| Valve Diameter, Intake | 2.08″ |
| Valve Diameter, Exhaust | 1.74″ |
| Carburetion | Single Carter 4-bbl |
| Air Cleaner | Unsilenced |
| Exhaust System | Dual exhaust |
| Fuel Recommended | Premium |
1968 Road Runner With a 426 Hemi
The 426 Hemi was available as an option for the 1968 Road Runner. The engine order code was 73 and cost an extra $714.30. Let’s take a look at the specifications.
| Specifications | 426 Hemi |
| Displacement | 426 |
| Bore and Stroke | 4.25″ x 3.75″ |
| Horsepower | 425 @ 5,000 RPM |
| Torque | 490 @ 4,000 RPM |
| Compression Ratio | 10.25:1 |
| Camshaft | High lift, long duration, high overlap |
| Cam Duration/Overlap | 284°/284°/60° |
| Cam Lift | .490″/.481″ |
| Lifter Type | Mechanical |
| Valve Diameter, Intake | 2.25″ |
| Valve Diameter, Exhaust | 1.94″ |
| Carburetion | Dual Carter 4-bbl |
| Air Cleaner | Unsilenced |
| Exhaust System | Dual, low restriction |
| Fuel Recommended | Premium |
That’s the complete list of engines available for the 1968 Plymouth Road Runner. If you have any questions to ask me about the engine options or specifications for the 1968 Road Runner car model, send us an email found specifically on my contact page or comment below.
About 38 years ago I assembled my first Mopar engine, it was for a 1970 ‘Cuda. It’s at that time my hands on experience with Mopar cars and engines, including the 440, started. Although my research of the engines started years earlier.
Read More B-body Road Runner Articles
1969 Plymouth Road Runner Engine Options and Specs
1970 Plymouth Road Runner Engine Options and Specs
1971 Plymouth Road Runner Engine Options and Specs
1972 Plymouth Road Runner Engine Options and Specifications
1973 Plymouth Road Runner Engine Options and Specifications
1974 Plymouth Road Runner Engine Options and Specifications
Article Resources
- 1968 Plymouth Service Manual
- Google Books: Chrysler Engines 1922-1998
- Wikipedia: Road Runner
