The AC Cobra, sold as the Ford/Shelby AC Cobra in the United States and often known colloquially as the Shelby Cobra in that country, is an American-engined British sports car produced intermittently since 1962.

Like many British specialist manufacturers, AC Cars had been using the Bristol straight-6 engine in its small-volume production, including its AC Ace two-seater roadster.  This had a hand-built body with a steel tube frame, and aluminum body panels that were made using English wheeling machines.  The engine was a pre-World War II design of BMW which, by the 1960s, was considered dated.  In 1961, Bristol decided to cease production of its engine and instead use Chrysler 331 cu in (5.4 L) V8 engines.  AC started using the 2.6 litre Ford Zephyr engine in its cars.

In September 1961, American automotive designer Carroll Shelby airmailed AC a letter asking them if they would build him a car modified to accept a V8 engine.  AC agreed, provided a suitable engine could be found.  Shelby went to Chevrolet to see if they would provide him with engines, but not wanting to add competition to the Corvette they said no.  However, Ford wanted a car that could compete with the Corvette and they happened to have a brand new engine which could be used in this endeavor: Ford's 260 in³ HiPo (4.2 L) engine – a new lightweight, thin-wall cast small-block V8 tuned for high performance.  Ford provided Shelby with two engines.

In January 1962, mechanics at AC Cars in Thames Ditton, Surrey fitted the prototype chassis CSX0001 with a 260 ci Ford V8 borrowed from Ford in the UK; the 221 ci was never sent.  However, early engineering drawings were titled "AC Ace 3.6".  After testing and modification, the engine and transmission were removed and the chassis was air-freighted to Shelby in Los Angeles on 2 February 1962.  His team fitted it with an engine and transmission in less than eight hours at Dean Moon's shop in Santa Fe Springs, California, and began road-testing.

At the end of the 1964 racing season, the Cobra was being outclassed in sports car racing by Ferrari.  Carroll Shelby decided he needed a bigger engine.  A big block Ford FE series 390 V8 was installed in a Cobra and the result was scary — the car was virtually undrivable.  It was decided that a completely new chassis was needed.  With the combined help of Ford’s computers and the experience of the AC engineers, the new MKIII was born, with 4-inch (100 mm) main tubes instead of 3-inch (76 mm) for the chassis, huge cross-braced shock towers, and coil springs all around.  This, along with a bigger 427 ci version of the FE, made the new AC Cobra MKIII an absolutely unbeatable 2,200 lb (1,000 kg) race car.  Specifically, the engine that was installed in the car was Ford's famed 427 FE NASCAR "Side-Oiler" V8, a power-house engine developing 425 bhp (317 kW) in its mildest street version.

Unfortunately, the car missed homologation for the 1965 season and was not raced by the Shelby team.  However, it was raced successfully by many privateers and went on to win races all the way into the 1970s.  The AC 427 Cobra, although a commercial failure when in production, has now become one of the most sought-after and replicated automobiles ever.

From Wikipedia, the free encyclopedia.