Advent of the Cobra 427 After losing the 1964 World Sportscar Championship to Ferrari's GTOs, and facing the imminent arrival of Corvettes in American sportscar classes,
Carroll Shelby commissioned a complete redesign of the Cobra 289 that resulted in the
Cobra 427. A new Mark III
ladder chassis and all-independent suspension were designed with input from both Ford and AC and extensive use of Ford's computer-assisted design resources. The revised chassis was better able to handle the output of Ford's 7-litre
"427" FE V8, and the new suspension provided more travel. The first MkIII chassis with 427 powertrain was built in October 1964, and the first finished Cobra 427 was shown to the public in Riverside, California in January 1965.
Cobra 427 homologation problem Shelby's next hurdle was to produce the 100 cars needed to have it homologated, but by late February only 53 cars had been built. The FIA declined to homologate either the Cobra 427 or Ferrari's new
250 LM for the 1965 season. Shelby was left to dispose of over 50 copies of a race car ineligible for the events it was designed for. He instructed AC to halt production of the cars, and converted approximately 30 of the racecars to street-legal S/C models. AC began looking for projects of their own that would make them less dependent on work coming from
Shelby American.
Related projects By this time some consideration had already been given to possible successors of the Ace and small-block Cobra. In 1962, with work on the AC Cobra already underway, AC had a planned successor to the Ace in development. A single prototype of the car, called the MA-200, was produced. The majority of the engineering work on the MA-200 was done by AC's Polish engineer and former
MIG designer, Zdzislaw Teofil (Z.T.) Marczewski, who had also developed a new flat-six engine to power the car. Late in the project the MA-200 was adapted to accept a Ford 289 gifted to AC by Ford—one of three special "Hi-Po" 289s prepared for Le Mans in 1963. Longer and wider than the Ace, the completed MA-200 was registered as 6000 PE on 19 November 1963, and became
Derek Hurlock's personal car. Additionally, two Cobras with entirely new bodywork by carrozzeria Ghia were shown at the Turin Auto Show in November 1965. The cars were built on chassis produced by AC Cars, but had Shelby American serial numbers CSX5001 and CSX5002.
Birth of the AC 428 With Ford taking an increasingly large role in the slow-selling Shelby Cobra, and both Ford and Carroll Shelby moving on to other projects, AC decided to adapt their existing MkIII chassis to create a new vehicle under their own control. In search of a carrozzeria to produce a body for the car, the Hurlocks first went to Bertone, then to Frua at the suggestion of
Hubert Patthey, the Swiss importer of AC cars. The body delivered by Frua is very similar in appearance to the
Maserati Mistral, also styled by Frua. The two cars share the front quarter windows and door handles. The bumpers and windscreen may also be shared. The first prototype, designated CF 1, had an unmodified MkIII suspension, and a removable metal tonneau cover behind the seats under which the hood was stored. The original engine in this car was a
Ford 390 V8, later replaced by a Ford "428" V8. CF 1 is reported to have had a light alloy body, although one reference reports that CF 1 had a steel body with aluminium bonnet and door skins. Production cars also had side vents added to the wings to exhaust hot air from the engine bay. For production cars, AC replaced the Cobra MkIII's competition-oriented suspension's spherical-joints with Metalastik bushings. AC's new car was first seen in drophead coupé form at the 1965 Earls Court motor show as the AC 427. AC's earliest advertising for the car also used the AC 427 name. Only two cars were built with the Ford "427" engine. By mid-1966, the AC 428 became available. A fastback coupé version debuted at Earls Court in 1967. Derek Hurlock is on record as saying "I like the 428 because it fits my image of a true GT Car." He also said "Like anything exclusive, especially from craftsmen, it costs a lot of money. For this you get one of the fastest cars on the road, guaranteed to make an impression anywhere, and backed by a small company that cares. This one AC that joined that select company of very fast, very luxurious touring automobiles which moved effortlessly from current model to collector's piece." The cars were built to
rolling chassis condition at AC's plant in
Thames Ditton, England, then shipped to Frua's workshop in Turin, Italy to have the body fitted, then sent back to England to have the powertrain and trim added. Production costs were high, and the cars could not be sold at a profitable price.
Production challenges and end of production The AC 428 was never fully developed because AC Cars lacked the financial means. The car's two most persistent problems were excessively high engine oil temperatures, and excessive engine heat transferring to the car's interior. Labour disputes in Italy dogged Frua, choking their output of bodies and preventing them from being able to fill AC's car orders in a timely fashion. After being warned by Ford that the "428" engine would only be available for another three years through a new UK distributor rather than direct sales, and facing fuel price shocks due to the
1973 oil crisis and increasingly stringent American emission standards, AC decided to end production. ==Features==