1971 Plymouth Road Runner Engine Options and Specifications

In 1971 the Plymouth Road Runner could be ordered with four different high performance engine options.

For the 1971 Road Runner, the 383 high performance 4 barrel engine was the standard engine. Three engine options were available including the 340 4 barrel, 440 6 barrel and the 426 Hemi.

This article will include the 1971 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.

1971 Plymouth Road Runner Engine Options and Specifications

1971 Plymouth Road Runner with a 383 engine.
1971 Plymouth Road Runner with a 383 engine

The 1971 Road Runner was available with the following four engines.

  • 340 4-barrel (Optional)
  • 383 4-barrel (Standard)
  • 440 6-barrel (Optional)
  • 426 Hemi (Optional)

In 1971 the 340 4 barrel engine was added to the Road Runner lineup for the first time. The 383 engine had a decrease in compression ratio and horsepower. The 440 Six Barrel had a slight decrease in horsepower and compression ratio. The 426 Hemi horsepower and compression remained the same.

1971 was the first year the manufacturers rated horsepower and torque with gross and net ratings.

1971 Road Runner with a 383 4-barrel

383 engine in a 1971 Plymouth Road Runner.
383 engine in a 1971 Plymouth Road Runner

Let’s begin with the specifications for the standard engine, the 383 4 barrel engine. The engine code was E65.

Of the four engines available for the 1971 Road Runner, the 383 had the largest reduction in horsepower and compression ratio compared to the year before.

Horsepower decreased from 335 to 300 gross and the compression ratio decreased from 9.5:1 to 8.5:1.

Let’s take a close look at the specifications.

Specifications383 4-barrel
Displacement383
Bore and Stroke4.25″ x 3.375″
Horsepower (Gross)
Horsepower (Net)
300 @ 4,800 RPM
250 @ 4,800 RPM
Torque (Gross)
Torque (Net)
410 @ 3,400 RPM
325 @ 3,400 RPM
Compression Ratio8.5:1
CamshaftHigh lift, high performance
Cam Duration/Overlap268°/284°/46°
Cam Lift.450″/.458″
Lifter TypeHydraulic
Valve Diameter, Intake2.08″
Valve Diameter, Exhaust1.74″
CarburetionSingle 4-bbl
Air CleanerDual Snorkel
Exhaust SystemDual, low restriction
Fuel RecommendedRegular
1971 Plymouth Road Runner 383 4 barrel Specifications.

1971 Road Runner With a 440 6-barrel

The 440 Six Barrel was available as an option for the 1971 Road Runner. The engine had a slight reduction in horsepower and compression compared to the previous year.

The engine code was E87 and cost an extra $262.15. Let’s take a look at the specifications.

Specifications440 Six Barrel
Displacement440
Bore and Stroke4.32″ x 3.75″
Horsepower (Gross)
Horsepower (Net)
385 @ 4,700 RPM
330 @ 4,700 RPM
Torque (Gross)
Torque (Net)
490 @ 3,200 RPM
410 @ 3,200 RPM
Compression Ratio10.3:1
CamshaftHigh lift, long duration, high overlap
Cam Duration/Overlap268°/284°/46°
Cam Lift.450″/.458″
Lifter TypeHydraulic
Valve Diameter, Intake2.08″
Valve Diameter, Exhaust1.74″
CarburetionTriple Holley 2-bbl
Air CleanerUnsilenced
Exhaust SystemDual
Fuel RecommendedPremium
1971 Plymouth Road Runner 440 Six Barrel High Performance Specifications.

1971 Road Runner With a 426 Hemi

426 Hemi engine in a 1971 Plymouth Road Runner.
426 Hemi engine in a 1971 Plymouth Road Runner

The 426 Hemi was available as an option for the 1971 Road Runner. Of all the 1971 Road Runner engines available, it was the only one that didn’t see any reduction in horsepower or compression ratio.

The engine code was E74 and cost an extra $883.55. Let’s take a look at the specifications.

Specifications426 Hemi
Displacement426
Bore and Stroke4.25″ x 3.75″
Horsepower (Gross)
Horsepower (Net)
425 @ 5,000 RPM
350 @ 5,000 RPM
Torque (Gross)
Torque (Net)
490 @ 4,000 RPM
390 @ 4,000 RPM
Compression Ratio10.25:1
CamshaftHigh lift, long duration, high overlap
Cam Duration/Overlap284°/284°/60°
Cam Lift.490″/.481″
Lifter TypeHydraulic
Valve Diameter, Intake2.25″
Valve Diameter, Exhaust1.94″
CarburetionDual Carter 4-bbl
Air CleanerUnsilenced
Exhaust SystemDual, low restriction
Fuel RecommendedPremium
1971 Plymouth Road Runner 426 Hemi Dual 4 barrel Specifications.

1971 Plymouth Road Runner With a 340 4-barrel

The 340 4-barrel was available as an option for the 1971 Road Runner for the first time. The rated horsepower for the 340 engine remained the same but saw a slight decrease in compression from the previous year.

The engine code was E55 and cost an extra $45.90. Let’s take a look at the specifications.

Specifications340 4-barrel
Displacement340
Bore and Stroke4.04″ x 3.31″
Horsepower (Gross)
Horsepower (Net)
275 @ 5,000 RPM
235 @ 5,000 RPM
Torque (Gross)
Torque (Net)
340 @ 3,200 RPM
310 @ 3,200 RPM
Compression Ratio10.3:1
CamshaftHigh lift, high performance
Cam Duration/Overlap268°/276°/44°
Cam Lift.429″/.444″
Lifter TypeHydraulic
Valve Diameter, Intake2.02″
Valve Diameter, Exhaust1.60″
CarburetionSingle 4-bbl
Air CleanerUnsilenced
Exhaust SystemDual, low restriction
Fuel RecommendedPremium
1971 Road Runner 340 4 barrel Specifications.

That’s the complete list of engines available for the 1971 Plymouth Road Runner. If you have any questions to ask me about the engine options or specifications for the 1971 Road Runner car model, send us an email found specifically on my contact page or comment below.

1971 Plymouth Road Runner.
1971 Plymouth Road Runner

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.

Kevin Garce B-body video including Road Runner cars.

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