1970 Plymouth Duster 340: Remembering Mopar's Giant-Slaying Mini Muscle Car

In my home country of Romania, as well as in most European countries, the Duster nameplate is famous thanks to an affordable crossover SUV marketed by Dacia (or Renault in some countries) since 2010.

Though my brain instantly processes that they're referring to the crossover, every time people say, " I drive a Duster," my muscle car-worshipping heart starts beating faster, and I start hearing the distinct rumble of a 340 small block in my ears.

Like the Dacia Duster, the Plymouth with the same model name was an affordable vehicle, but unlike the crossover, it became an icon that turned more teenagers into life-long muscle car fanatics than any other compact from its era.

Breathing new life into the A-body platform

For the 1970 model year, Plymouth decided to redesign its popular Barracuda pony car, moving it from the venerable A-body platform to the new E-body, which was better suited for accommodating big-block V8s like the 440 and HEMI.

The A-body remained in use for the popular third-generation Valiant. Still, despite Plymouth's effort to deliver a fun two-door version with the Scamp, the compact lineup failed to attract younger buyers.

To change that, the Chrysler division decided to spend $15 million (nearly $120 million in 2023) on designing a new two-door, Valiant-based model, and thus the Duster (initially advertised as Valiant Duster) was born.

Standard Valiant in the front, Coke bottle-styled, semi-fastback in the rear

Designed by Milt Antonick and Neil Walling, the Duster used the same front end as the Valiant it was based on, but from the cowl to the rear bumper, everything was new.

Set to compete with the Chevy Nova, Ford Maverick, or AMC Hornet, the new compact looked like a slightly scaled-down muscle car thanks to its beautiful Coke bottle-styled semi-fastback roofline.

The handsome little Duster was available in two trims: the base, which started at $2,172, offering a standard 198-ci (3.2-liter) Slant-6, an optional 225-ci (3.7-liter) version of the six, or a 318-ci (5.2-liter) V8, and the more potent, V8-powered Duster 340 priced at $2,547.

The gateway Mopar muscle for performance enthusiasts

Created using the same recipe that made the Road Runner a sales sensation, the Duster 340 was an affordable, entry-level muscle car that delivered honest performance and an appealing design for a great price.

Visually, only the standard rally wheels, side decals, and specific "twister" logos helped distinguish the 340 from the standard Duster. There was no scooped hood, spoilers, or air vents.

In keeping with Plymouth tradition, those logos were supposed to feature the Tasmanian devil cartoon character, but a failed deal with the Warner Brothers studio resulted in a different graphic.

Though it looked much like a standard Slant-6-powered Duster, the 340 was no ordinary compact. As standard, it had a beefed-up rear suspension, front disc brakes, and a powerful performance-oriented small block V8 rated at 325 hp.

Even if it wasn't a 440 Six-Barrel or a 426 HEMI, the 340-ci (5.2-lites) engine featured hammer-forged steel connecting rods, high-compression cast aluminum pistons, and a four-barrel carburetor mounted on top of a high-rise, dual-plane intake that fed high-flow cylinder heads.

The capable engine was paired with a standard three-speed manual, while a four-speed and a three-speed TorqueFlite were available on the order form.

A giant-slaying compact

Combined with the relatively lightweight compact body and chassis combo, the V8 made the Duster 340 a legitimate muscle car that could hang with the big boys and sometimes even beat them over a quarter mile.

As Mopar connoisseurs can attest, the 340 V8's actual output was purposefully understated to avoid high insurance premiums. So, instead of 275 hp, the engine delivered closer to the 325 hp mark when put on the dyno.

With its excellent power-to-weight ratio and optional factory hardware like a four-speed and 3:91 rear end containing a Sure-Grip limited-slip diff, the Duster 340 could embarrass larger, more expensive muscle cars as soon as it left the dealership.

Able to run the quarter mile in the high 13-second range, it was quicker than any 1970 Ford, 350-hp SS 396 Chevy Chevelle, or the 440 Pontiac GTO and Firebird.

HEMI or 440 Six-Pack Mopar siblings were faster, but if the 340 received some simple bolt-on upgrades like aftermarket headers and a bigger 750-cfm Holley carb, the little Duster could more than keep up.

Increasingly saught-after today

In 1970, word of the Duster 340's performance potential spread like wildfire, so 24,817 examples were sold during its debut model year.

The rabid compact was revered by its owners and feared by the rest of the muscle car crowd, who rarely dared to pull up alongside one at a stop light, especially at night.

However, in the following decades, the Duster 340 was forgotten by most performance enthusiasts who preferred newer models or more popular nameplates from the golden age of muscle cars.

These days, the mighty little Plymouth is becoming popular once again. If a highly original, well-kept 340 was worth around $15,000 only five years ago, its value has more than doubled and shows no signs of stagnating.

Still, when more casual muscle car fans start talking about the most impressive models from the sixties and seventies, the Duster 340 rarely comes up.

Now that you know more about it, you can remind everyone that, apart from the 'Cudas and Road Runners, Plymouth built one of the most impressive compacts of the era.

If you want to take a virtual tour of the 1970 Duster 340, we recommend the following video by Lou Costabile.