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Shelby AC Cobra Mark III

Shelby AC Cobra Mark III

Development of the Shelby AC Cobra

The Shelby AC Cobra was a car that Carroll Shelby put together around 1961, using a modified AC Ace chassis and a Ford engine.

The AC Ace was a two-seater roadster with a hand-built steel tube frame, and aluminum body panels, made by AC in England. In 1961 the Bristol straight-6 engines used by AC had just been discontinued, and AC replaced them with 2.6 L Ford Zephyr engines. That same year Shelby asked AC to build him a car modified to accept a V8 engine, and AC agreed.

When Shelby started looking for a suitable engine, Ford backed Shelby’s project as a way to compete with Chevrolet’s Corvette. Ford supplied Shelby with their brand-new 260 in³ HiPo, 4.2 L engine, a lightweight, thin-wall cast small-block V8 tuned for high performance.

AC exported completed, painted and trimmed cars (without engine or gearbox) to Shelby, who finished the cars in his workshop in Los Angeles.

Beating the Corvette

Shelby wanted the Cobras to be ‘Corvette-Beaters’, and at nearly 500 lb (227 kg) less than the Corvette, the Cobra achieved that goal at Riverside International Raceway on February the 2nd, 1963. Dave MacDonald drove his car past a field of Corvettes, Jaguars, Porsches, and Maseratis, recording the Cobra's first victory.

Shelby AC Cobra Mark III

The Cobra Mark III was designed in cooperation with Ford, and had a chassis built with 4-inch (102 mm) tubes instead of the 3-inch (76 mm) tubes previously used. It also sported coil spring suspension all around, and the rack and pinion steering inherited from the Mark II Cobra.

Other changes included wide fenders and a larger radiator opening, as well as Ford’s 427 engine (7.0 L). The 427 engine offered a power of 425 bhp (317 kW) and a top speed of 164 mph (262 km/h) in the standard model, and 485 bhp (362 kW), 185 mph (298 km/h) in the competition model.

Cobra Mark III production began on January the 1st, 1965. Cars were sent to the US as unpainted rolling chassis, and they were finished in Shelby's workshop.

Chassis numbering

The Cobra chassis were coded CSX, where the ‘SX’ stands for ‘Shelby eXport’. The four following numbers ran from CSX2000 sequentially for the Mark I and Mark II Cobras, and from CSX3000 for the Mark III Cobras, the 3 signifying coil spring suspension.

Cobra name rights

A joint press release from AC/Angliss (owner of a Cobra parts reseller and replica car manufacturer), after a lawsuit from Carroll Shelby in 1982, acknowledged that Carroll Shelby was the manufacturer of record of all the 1960s AC Cobra automobiles in the United States and that Shelby himself is the sole person allowed to call his car a Cobra.