AC Cobra 427 Competition

While packing in Europe and north and South America throughout the Fifties, Caroll Shelby liked a dream; construction of the fastest sportscar of the world. From here 1956 when it had already proposed a name for its car, it to be called Cobra. Shortly after his 1959 24 hours of victory of Mans for Aston Martin, Shelby was struck by problems of heart. Little laid out to make thus, it was forced to give up the engine packing like driver. This gave him the hour to make its dream come true.

Early in the 1950s John Tojeiro designed small sportscar, which was sold under the AC Ace name. Installed in the simple but effective tubular chassis was the Bristol 2 litre six cylinder engine. This unit was derived from BMW's 328 engine and its design dates back to 1919. Its lightweight chassis and body, and effective engine made the Ace a moderately successful racer. When Bristol announced that the 2 litre engine would be phased out, AC was left without an engine to power the Ace. Previous attempts to install other engines, like American V8s had failed miserably and the end of the Ace production was announced.

When Shelby read about the end of the AC Ace, he immediatly contacted AC and his long time associates Ford. He convinced AC to continue constructing the Ace and Ford to supply special versions of their Fairlane engine for installation in the AC chassis. Shelby flew over to the UK to supervise the construction of the prototype chassis, which featured modifications designed by Shelby to ensure the hybrid would be driveable.

Although the displacement of the Ford '260' V8 was more than twice as large and the initial 260 bhp output almost twice as large as the Bristol's, the Ford unit weighed less. Main diffuculty in incorporating American V8 engines was their rather high torque figures. The rear-end needed considerable modifications to handle the torque produced by the Ford. With the beefed up rear suspension, the AC chassis took to the Ford V8 engine surprisingly well and after extensive tests 100 chassis/bodies and Ford V8s were ordered. Shelby's Cobra was born!

The V8 Ford engines were derived from the ones used in the Fairlane and Fairlane 500, but they were delivered to Shelby in a somewhat 'tweaked' form. Breathing through a single Holley Carburetor and fitted with 'hotter' cams, solid tappets and larger ports, the V8 was good for around 260bhp. For competition use Shelby modified the engine even further. With an increased compression ratio and breathing through four twin-choke Webers figures of 335 bhp could be achieved, with the engine revving up to 9000 rpm. Stunning performance was the result of this very powerful engine, which is reflected by the acceleration and top speed figures. Had Shelby succeeded in building the world's fastest sportscar?

In the mean time, the world's largest manufacturer and Ford's biggest competitor, General Motors worked intensively on building their fastest GT-racer yet. Dubbed Sting Ray, the fastest Corvette to date was set to make its debut at the 1962 Riverside 3-hour race for Grand-Touring cars. Coincedently Shelby's workshop was around the corner of the Riverside track and his competition Cobras were about ready to make their debut as well. So in a weird twist of fate, both GM's and Ford's latest racers made their debut in the same race. In qualifying Shelby took the wheel of one of the two Cobras entered and shocked the crowd and even more so GM's racing division by lapping over four seconds faster than the fastest Sting Ray. In the race Bill Krause (pictured above) had built up a lead of over 30 seconds in the first 30 minutes. He was forced to retire when a wheel came off and in doing so he handed the victory to one of the Sting Rays. A legend was born that day, but it wasn't the Sting Ray!

Vowing to decimate the Sting Rays in the following season, Shelby and his Cobras took part in the first US manufacturers' championship. The Cobra's dominance was total and Shelby took the title with 111 points over Ferrari's 28 and Chevrolet's 19. All but one of the seven races of the championship were won by a Cobra. After this big US success, Shelby set out to take on Ferrari in Europe with more powerful and coupe bodied versions of the Cobra. He succeeded and scored class victories at LeMans and in 1965 the World GT Championship was his, a mere three years after the Cobra's birth.

Caroll Shelby decided to up the ante once more by installing the 7 litre V8 that had powered the GT40 to the Le Mans win in the Cobra chassis. The added power and weight required some serious modification ranging from increased tubes for the frame and fully independent suspension at the back. To get the power on the road wider tyres were also fitted, which required bigger wheelarches, considerably increasing the width. The most potent version of the 427 engine available for competition use produced in the region of 550 bhp.

Although the FIA was lenient with homologation in the past, they had become very strict after Ferrari tried to get the 250 LM homologated and told Shelby at least 100 Cobra 427s built within a year were required to pass the homologation. Unfortunately when the FIA dropped by the workshop, there were only 53 examples completed and the homologation was refused. Of the 53 just 16 were already sold to customers in full competition spec. Three more cars of the same spec were retained by the factory and the remaing 34 were sold to the public as S/C or Semi Competition model ford road use. In the following years another 250 seven litre Cobras were produced, but it was too late for homologation.

Featured is CSX 3017; a highly original example of the 16 competition 427 Cobras sold. It was successfully campaigned in the 1966 by the Ford of Canada works driver George Eaton. Despite being only twenty years old he coped with the 550 bhp remarkably well, winning his class in all eighteen regional and national races he competed in. In a 6 Hours race at Mosport he even beat his team's Ford GT40. It has since survived virtually undamaged with the original and body still fitted. Painted in familiar Cobra colours, the very rare 427 Cobra is seen in action here at the 2006 Monterey Historic Races.

General specifications
Record last updated 01 / 22 / 2007
Country of origin Great Britain
Produced in 1965
Numbers built 19
Body design N/A
Weight 975 kilo / 2149.5 lbs

Drivetrain
Engine Ford 427 90º V 8
Engine Location Front , longitudinally mounted
Displacement 6.997 liter / 427 cu in
Valvetrain 2 valves / cylinder, OHV
Fuel feed Holley 780 CFM Carburetor
Aspiration Naturally Aspirated
Gearbox Ford 4 speed Manual
Drive Rear wheel drive

Performance figures
Power 550 bhp / 410 KW @ 6700 rpm
Torque 640 Nm / 472 ft lbs @ 3700 rpm
BHP/Liter 79 bhp / liter
Power to weight ratio 0.56 bhp / kg
Top Speed N/A
0-60 mph Acceleration N/A