Plymouth RoadRunner 1970 – “440 Six Pack” Cruisin’ The Coast 2015

The 440 Six Barrel gave the 1970 Road Runner three two-barrel carburetors, 390 horsepower, 490 lb-ft of torque, and a Dana 60 rear axle — the same hardware the mid-1969 A12 package introduced with its pinned-down fiberglass hood and hubcap-less steel wheels. Just 1,815 were built for 1970, and it ran the quarter mile in the low thirteens. Read on for why it was the smarter buy than a Hemi.

Plymouth built the Road Runner around a single clear idea: performance that a young buyer could actually afford, with the money spent on the drivetrain and nowhere else. Which makes the 440 Six Barrel version something of a contradiction sitting in a parking lot. Check that option box and you got a black fiberglass hood held down by four exposed pins, a scoop wearing warning-label graphics, and steel wheels with no hubcaps whatsoever, as though Plymouth wanted the car to look stripped even while hiding one of the most serious engines it ever sold to the public. Three carburetors sat under that scoop. By 1970 Plymouth had dropped the theatrics and made the Six Barrel a straightforward order-sheet option, but the engine underneath never lost its edge. Very few cars ever left the factory either way, and the reason is not the one most people assume.

What the A12 Code Actually Bought You

The package launched mid-1969 under code A12, and it was not a trim level so much as a complete engineering decision. For 1970 Plymouth carried the same drivetrain forward as the V-code 440 Six Barrel, a regular option rather than a package unto itself. At its centre sat a 440-cubic-inch V8 fed by three Holley two-barrel carburetors mounted on an Edelbrock aluminum intake manifold, officially rated at 390 horsepower at 4,700 rpm and 490 lb-ft of torque at 3,200 rpm. Behind it went a Dana 60 rear axle with 4.10 gearing, a component chosen because Chrysler’s engineers understood that anything less would not survive the torque this engine produced when used the way buyers intended to use it.

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Three Carburetors and How They Work Together

The three-carburetor arrangement is more sophisticated than it first appears. The centre carburetor handles all normal driving on its own, giving reasonable manners and tolerable fuel consumption around town, while the outer two remain closed. Under hard throttle they open progressively, and total flow jumps dramatically. The result is an engine that behaves like a mild large-displacement V8 in traffic and then transforms completely when asked, which is a far better solution for a street car than a single enormous carburetor that compromises everywhere in exchange for peak flow.

The Hemi Alternative That Made More Sense

The 440 Six Barrel existed because of the Hemi’s price. The 426 Hemi was the ultimate Chrysler engine and it cost roughly twice as much as a 440, required regular valve adjustment, and was genuinely unpleasant in city driving. The Six Barrel offered something close to the Hemi’s real-world street performance for a fraction of the money and with far better manners, and in stock trim on the street the gap between them was much narrower than the badge value suggests. For a buyer spending their own money, it was frequently the smarter choice.

A Hood You Had to Carry to the Ground

The visual presentation on those 1969 A12 cars was deliberately raw. The lift-off fiberglass hood was finished in matte black regardless of body colour, secured by four chrome pins with no hinges at all, meaning the entire panel had to be removed by hand to reach the engine. Chrome trim was minimal, and the car rode on plain 15×6-inch steel wheels with chrome lug nuts and no covers of any kind. Plymouth was signalling that money had gone into hardware rather than decoration, and the aesthetic has aged into one of the most recognisable looks of the entire era. The 1970 cars went back to a conventional steel hood, with the vacuum-operated Air Grabber scoop sitting on the options list instead.

The Cheap Muscle Car That Changed Everything

The Road Runner itself was built on a premise that seems obvious now and was not in 1968. Plymouth stripped a Belvedere to its essentials, fitted a purpose-built 383 with 440 cylinder heads and camshaft, deleted almost every comfort feature, licensed the cartoon character from Warner Bros. for a reported sum, and priced the whole thing under three thousand dollars. It sold far beyond expectations and forced every competitor to build a cheap performance model in response. The A12 sat at the top of that range while keeping the same fundamental honesty.

Fewer Than Two Thousand Cars

Production numbers for the 1970 Six Barrel cars are small. Plymouth built 1,815 of them for the model year, split into 1,130 hardtops, 651 coupes and just 34 convertibles, out of Road Runner production that had already fallen to under 37,000 cars. The mid-1969 A12 run was smaller still at 1,412. The option was expensive relative to the car’s positioning, and buyers who could afford the jump often stretched further to the Hemi for the prestige. That combination of high cost and modest appeal at the time is exactly what makes surviving examples scarce and desirable now.

Low Thirteens Straight Off the Lot

Performance in period testing was genuinely serious. Magazine road tests of Six Barrel cars recorded quarter-mile times in the low thirteens, with some runs dipping below, on the bias-ply tires of the day and with no modification beyond a proper launch. That figure put the Six Barrel Road Runner among the quickest cars anyone could buy over a counter in 1970, and it did so at a price well below the Hemi cars and most of the competition from General Motors and Ford.

What Breaks and What Never Does

Ownership today involves a few specific realities. The fiberglass hood is fragile, expensive to replace, and frequently damaged, so an original undamaged panel adds meaningful value. The outboard carburetors need periodic attention and are commonly replaced with a single four-barrel by owners who tire of tuning them, which means a car with its complete correct induction system intact is worth seeking. The Dana 60 is essentially indestructible and rarely a concern. As with any Six Barrel car, the fender tag and build documentation do the work that visual inspection cannot.

The Budget Car That Became Blue Chip

The result is a car that has aged into something Plymouth never quite intended. It was built as the affordable option, the sensible alternative to the Hemi, and it was sold to people who wanted speed rather than status. Half a century later it is a blue-chip collector car with a look that nothing else replicates, and the very features that made those first A12 cars seem cheap, the pinned hood and the bare steel wheels, are now the details everyone recognises first. Honest engineering tends to hold up better than decoration does.

Six Barrel or Hemi, which would you have ordered in 1970? Share your thoughts in the comments below.

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