Ultra-exclusive Shelby Cobra ready to strike

Shelby Cobra. Photo / Supplied

It's going to be one of the most exclusive cars built - the 50th anniversary edition of the Shelby Cobra, the open-top flyer with a V8 American heart beating inside a contoured British body.

Only 50 will be built - one for every year of the marque's existence - and the order book has just been opened for the car's launch in the United States next year.

The first of the limited-edition Cobras was unveiled as a rolling chassis (without engine or gearbox) at the glitzy Barrett-Jackson car auction in Arizona.

The fibreglass-bodied rolling chassis will cost US$69,995 ($90,700) and the aluminium-bodied version US$134,995. The engine and gearbox is extra.

The original AC Cobra first appeared in 1962 at the New York motor show. It was an Anglo-American design, the work of American racer Carroll Shelby and AC Motors of England.

It was based on the AC Ace, an all-alloy sports racer with a tubular frame that had enjoyed race success in Britain and Europe in the 1950s.

Shelby imported the car into the US, replaced its 2-litre straight-six, British-built Bristol engine with an American Ford small-block V8, and created an icon: the AC Cobra, later known as a Shelby or Shelby Cobra.

"Fifty years after its introduction, the Shelby Cobra is still an international symbol of high performance," said John Luft, president of Shelby American.

"Combining a robust, powerful American engine with a lightweight European chassis was brilliant. The Cobra remains one of the most coveted cars in the world," said Luft.

Like some of Shelby's other modern Cobras, the 50th anniversary cars are regarded as continuation series cars, and are given a Shelby serial number, starting with the hallowed "CSX" designation.

Each model will be painted Shelby Black, contrasting with the wine-coloured interior and its leather-trimmed seats. A commemorative disc sits in the centre of the steering wheel.

The AC Cobra story began in the late 1950s. Shelby had seen the lightweight aluminium-bodied AC Ace while racing in Europe and, on returning to the US, wrote to AC Motors asking if it would build an Ace to accept a V8 engine. AC agreed, provided a suitable V8 could be found.

The story goes that Shelby first went to Chevrolet for an engine. But Chevrolet didn't want competition for the Corvette and said no.

Shelby went to Ford. Ford was looking for something to compete with the Corvette. It was pre-Mustang days and it happened to have a new small-block V8 engine available, a 4.2-litre (260cu in) Windsor unit tuned for high performance.

Shelby airfreighted the engine to England and AC Cars fitted it into the prototype chassis CSX0001. The car and drivetrain was tested and modified and once AC Cars was happy with its performance it removed the engine and gearbox and airfreighted the chassis to Shelby in Los Angeles on February 2, 1962.

Shelby's team installed the new drivetrain in less than eight hours and began road-testing. Production of the AC Cobra Mk I began soon after.

The first 75 models were fitted with the 4.2-litre Ford engine. The remaining 51 Mark I models used a larger version of the Windsor Ford V8, the 4.7-litre (289cu in) unit.

Later that year AC Cars' engineers reworked the car's front end but stayed with the leaf-spring suspension. They reportedly borrowed a new steering rack from Britain's MGB and a steering column from the Volkswagen Beetle and called it the AC Cobra Mk II. It entered production in 1963. More than 500 Mk II models were built through to July 1965.

Meantime, the leaf-spring Cobra Mk II was losing its edge on the track in the US. Shelby tried a 6.3-litre (384cu in) Ford engine but the chassis couldn't cope with the extra oomph.

The experiment ended with a new chassis designated the Mk III and designed at Ford HQ in Detroit. It used wider diameter tubing in the frame and sat on coil springs. The bumpers were wider and the radiator opening larger.

Under the bonnet was a 7-litre (427cu in) V8 delivering 317kW in the standard model and 362kW in the racer. Top speed was just shy of 300km/h. Production began at AC Cars in England on January 1, 1965. The AC Cobra 427s were sent to the US as unpainted rolling chassis and finished in Shelby's workshop.

But the Mk III did not sell well. To save money, say the history books, most AC Cobra 427s were fitted with Ford's lower-cost 428 engine, a smaller bore unit intended for road use rather than racing.

Around 300 Mark III cars were sent to Shelby in the US during the years 1965 and 1966, including the competition versions. The MK III missed approval for the 1965 racing season and was not raced by the Shelby team. It was raced successfully by privateers and went on to win into the 1970s.

The historic value of the Mk III lies in a shipment of 31 competition cars. They remained unsold and sat around in the 1960s before being detuned, made road worthy and called S/C for semi-competition.

These cars today sell for around $2 million.