Plymouth Duster 340

Plymouth Duster 340 at a glance

The Duster 340 belongs to our Plymouth catalogue and to the golden age of the American muscle car guide.

A Valiant with a new shape

Plymouth created the Duster in a program to update the Valiant. The Duster shared the Valiant's front sheet metal, but from the scuttle back the body was new: a two-door coupé with a sloping, semi-fastback roofline. It was introduced in late 1969 as a 1970 model, and by 1971 production had reached 186,478 cars.

The formula was the same as for the bigger muscle cars, only on a smaller scale: a light body with the strongest small-block V8. Plymouth gave the Duster 340 stripes and, later, a shark-tooth grille. The cheaper Twister package of 1971 copied that look with the six-cylinder or the 318 V8.

The 340 V8

The 340 was rated at 205 kW (275 hp) SAE gross in 1970 and 1971, equivalent to 175 kW (235 hp) net. In 1971, 12,886 Dusters were built with it, about seven percent of the year's total. Electronic ignition became optional late in 1971 and standard on 340 models in 1972.

For 1972 the compression ratio dropped from 10.2:1 to 8.5:1 and the intake valves shrank from 2.02 to 1.88 in. The source also mentions 183 kW (245 hp) for that year in the text, while its power table lists 179 kW (240 hp). From 1973 all 340s received an 8.25 in rear axle with a 5-on-4.5 in bolt pattern instead of the older 8.75 in design, and single-piston sliding disc calipers replaced the four-piston Kelsey-Hayes units.

Duster 360 (1974–1976)

For 1974 the 340 was replaced by the 360 V8 (code E58), offered as a separate model and rated at 183 kW (245 hp, SAE net). It was detuned for emissions but kept the 340's camshaft, cylinder heads, intake, carburettor and dual exhaust. Standard equipment included power disc brakes, full-length side stripes, heavier suspension, an extra anti-roll bar and an 8.25 in axle. Plymouth built 3,969 Duster 360s in 1974, most with automatic gearboxes; 1974 was also the Duster's best year overall, with 281,378 cars.

In 1975 the 360 still had no catalytic converter and used air injection instead; fewer than 2,000 Dusters were built with it. For 1976 the separate model was dropped and the 360 became an option on any Duster; about 1,300 cars received it. One 1976 car with 3.21 gearing reached 60 mph in 7.9 seconds.

Other Dusters and the end

Besides the performance models, Plymouth sold the Gold Duster with extra trim and a vinyl roof, the lightweight Feather Duster of 1975 with aluminium parts and up to 36 mpg on the highway, and from 1973 the Space Duster with a fold-down rear seat. In mid-1976 the Plymouth Volare replaced the Duster in the United States.

Dodge sold the same body as the Demon and Dart Sport. For the bigger Plymouth muscle cars of the same years, see the Plymouth Road Runner and the Barracuda, and compare all of them in the muscle car rankings.

Duster 340 or Duster 360?

The two cars are often compared, but their published figures are not. The 340 of 1970–1971 was rated gross, the 360 of 1974–1976 net, and the same engine reads clearly lower in net. The 1972–1973 340 shows the effect: on paper it lost 26 kW against 1971, mostly because of the new rating method and the lower compression. Between the two net-rated engines, the 1974 360 had 4 kW more than the 1972–1973 340.

For a driver the early 340 with its higher compression is the stronger engine; for a collector the 1974–1976 360 is the rarer one, with only about 1,300 built in its final year. Both share the light A-body, which is the reason the Duster was quick for its price.

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