The AC Cobra, sold in the United States as the Shelby Cobra and Shelby AC Cobra, is a sports car manufactured by British company AC Cars, with a Ford V8 engine. It was produced intermittently in both the United Kingdom and later the United States from 1962 to 1967.
History and development AC Cars had been building small numbers of its AC Ace two-seater roadster since 1953. The Ace had a steel ladder chassis with diameter tubular main rails, and a hand-built body of aluminium panels shaped using English wheeling machines. The Ace had used three different straight-six engines over its production life, starting with AC's own Light Six, then Bristol Cars six derived from the pre-war BMW M328, and finally a Ford Zephyr 6 engine. The Zephyr 6 was low enough that it allowed AC to restyle the nose of the car, lowering the hoodline, adding a smaller air intake, and removing the "moustache" lines below the headlamps on earlier cars.
In September 1961, Ford provided Shelby with two of its new small block V8 engines, one of which was shipped to AC in England.
AC Ace 3.6 In January 1962 mechanics at AC Cars in Thames Ditton, Surrey completed the "AC Ace 3.6" prototype with chassis number CSX2000.
AC had already made most of the modifications needed for the small-block V8 when they installed the Ford Zephyr 6 engine, including the extensive rework of the AC Ace's front end bodywork. The only modification of the front end of the first Cobra from that of the "AC Ace 2.6" was the steering box, which had to be moved outward to clear the wider V8 engine.
A significant modification was the fitting of a stronger rear differential to handle the increased engine power. In the place of the old E.N.V. unit was a Salisbury 4HU differential with inboard disc brakes to reduce unsprung weight—the same unit used on the Jaguar E-Type.
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.
By this time the small-block's displacement was increased to . Shelby's team installed the engine and a transmission into CSX2000 in less than eight hours at Dean Moon's shop in Santa Fe Springs, California, and began road-testing.
Production (CSX/CS 2001–2602)
A few changes were made to the production version: The inboard brakes were moved outboard to reduce cost. The fuel tank filler was relocated from the fender to the center of the trunk. The trunk lid had to be shortened to accommodate this change.
AC exported completed, painted, and trimmed cars (less engine and gearbox) to Shelby who then finished the cars in his workshop in Los Angeles by installing the engine and gearbox and correcting any bodywork flaws caused by the car's passage by sea. A small number of cars were also completed on the East Coast of the US by Ed Hugus in Pennsylvania, including the first production car; CSX2001.
The first 75 Cobra Mk1 models (including the prototype) were fitted with the Windsor Ford V8 . The remaining 51 Mk1 models were fitted with the larger version of the engine. After the 289 became available, Shelby offered an upgrade to the earlier cars. Most accepted the upgrade so cars with the 260 CID engine are rare today.
In late 1962, Alan Turner, AC's chief engineer, completed a major design change of the car's front end to accommodate rack and pinion steering while still using transverse leaf spring suspension (with the leaf spring doubling as the upper suspension link). The new car entered production in early 1963 and was designated Mark II. The steering rack was borrowed from the MGB while the new steering column came from the VW Beetle. About 528 Mark II Cobras were produced from 1963 to the summer of 1965. The last US-bound Mark II was produced in November 1964.
European model (COB/COX 6001–6062)
The Ace 2.6 was discontinued in 1963 to keep production focused on building cars for Shelby American Inc. To supply cars to the European market, AC began to market and sell the Cobra in Europe. Advertisements from the time state that the Cobra was designed to meet the requirements of Shelby American Inc.
Chassis CSX2196
Shelby experimented with a Ford FE engine in chassis CSX2196. The car did not receive the development it needed, as all available resources were committed to taking the crown from Ferrari in the GT class. Ken Miles raced the FE-powered Mark II at Sebring and pronounced the car virtually undrivable, naming it "The Turd". The car retired early with a failed engine.
CSX2196 was revised for the showdown at Nassau, where a more relaxed division of racing classes allowed the Cobras to run against a prototype Ford GT40, GM Grand Sport Corvettes and a Lola Mk6. An aluminium engine was used. By the end of the first lap, the Cobra had a lead the length of the start-finish straight. However, the car failed to finish due to brake problems.
Cobra 427
A new chassis, designated Mark III, was designed in cooperation with Ford in Detroit. The Mark III chassis was built using main chassis tubes, up from , and coil spring suspension all around (an especially significant change up front, where the previously used transverse leaf spring had done double duty as the top link). The new car also had wide fenders and a larger radiator opening. It was powered by the Ford FE "side oiler" engine equipped with a single 4-barrel 780 CFM Holley carburetor rated at at 6000 rpm and at 3700 rpm of torque, which provided a top speed of in the standard model. The more powerful semi-competition (S/C) model was tuned to , and had a top speed of .
Competition models (CSX/CSB 3001–3100)
Cobra Mark III production began on 1 January 1965; two prototypes had been sent to the United States in October 1964. Cars were sent to the US as unpainted rolling chassis, and they were fitted with engines and finished in Shelby's workshop.
Unfortunately, the MK III was not homologated for the 1965 racing season and was not raced by the Shelby team. Only 56 of the 100 cars required were produced when the FIA arrived in April, making these competition cars difficult to sell. Of those, 31 unsold competition models were fitted with windscreens and production dual-quad, side-oiler R-code 427s for street use. Called S/C for semi-competition, an original example can currently sell for US$1.5 million, making it one of the most valuable Cobra variants.
Production models (CSX/CSB 3101–3360)
Some 260 Cobra 427s were produced as street cars. The first 100 were fitted with fitted with dual-quad, top-oiler 427s and the next 105 or so were fitted with Ford's 428 FE engine. With a longer stroke and smaller bore than the 427, the oversquare V8 was a lower-cost engine intended for road use rather than racing, but in 1966 Police Interceptor trim made some 360hp. The final 55 cars reverted to the 427 side-oiler, but with the single 4 barrel carburetor on most of these late cars.
The AC Cobra was a financial failure that led Ford and Carroll Shelby to discontinue importing cars from England in 1967.
AC 289 Sports (COB/COX 6101–6132)
AC Cars kept producing the coil-spring AC Roadster with narrow fenders and a small block Ford 289. It was built and sold in Europe until late 1969.
Packages Dragon Snake Shelby offered a drag racing package, known as the Dragon Snake, which won several NHRA National events with Bruce Larson or Ed Hedrick at the wheel of CSX2093.
Only six 289 Dragon Snake Cobras were produced by the factory: "2019", "2357" as factory team cars, and "2248", "2416", "2427", "2472" as private team cars. One 427 Dragon Snake, 3198, was produced.
Cobras were also prepared by customers using the drag package. Examples include: "2075", "2093", "2109", "2353", and 3159 "King Cobra."
Slalom Snake
Designed for auto-cross events, only two examples were produced, the CSX2522 "Slalom Special", and the CSX2537 "Slalom Snake". Both had white exterior paint (with red racing stripes) and red leather interiors.
Equipped almost identically to CSX2522, the second example had aluminum valve covers, a tuned air cleaner, a Smiths heater, seat belts, front and rear brake cooling ducts, a hood scoop, side exhausts and a painted roll bar (2522's roll bar was chromed). Suspension options included Koni shock absorbers, front and rear anti-roll bars, unpolished six-inch magnesium pin-drive wheels, and Goodyear Blue Streak Sports Car Special tires.
Super Snake
In 1966, CSX 3015 S/C, originally part of a European promotional tour, was converted into a special model called the Super Snake, the "Cobra to End All Cobras." This conversion called for making the original racing model street legal with mufflers, a windshield and bumpers amongst other modifications. But some things were not modified, including the racing rear end, brakes and headers. The most notable modification is the addition of Twin Paxton Superchargers, TPS.
Shelby crafted a second model, CSX 3303, from a street version. CSX 3303 was given to comedian Bill Cosby, his close friend. When Cosby attempted to drive CSX3303, he found very difficult to control; he later recounted the experience on his 1968 stand-up comedy album 200 M.P.H.. Cosby gave the car back to Shelby, who then shipped it out to one of his company's dealers in San Francisco, S&C Ford on Van Ness Avenue. S&C Ford then sold it to customer Tony Maxey. Maxey had his throttle stick while leaving a traffic stop, lost control and drove it off a cliff, landing in the Pacific Ocean waters.
Shelby used CSX 3015 as a personal car over the years, sometimes entering it into local races like the Turismos Visitadores Cannonball-Run race in Nevada, where he was "waking [up] whole towns, blowing out windows, throwing belts and catching fire a couple of times, but finishing." CSX3015 was auctioned on 22 January 2007, at the Barrett-Jackson Collector Car Event in Scottsdale, Arizona, for $5 million (~$ in ) plus commission (£2.8 million), a record for a vehicle made in the U.S.
Adaptations (CF/CFX 01–80)
AC produced the AC 428 Frua on a stretched Cobra 427 MK III coil spring chassis with a steel body designed and built by Pietro Frua. The car was built until 1973.
(EF/EFX 501–509)
The American Electric Car Company used an even more extensively modified chassis for their vehicles. A single EFX chassis was supplied to the United Kingdom with an engine and gearbox fitted.
GHIA SPYDER
(CSX 5001–5002)
One prototype chassis (CSX 3063) was shipped to Ghia in Italy in 1965 for a body styling exercise. This vehicle was first displayed during a European car show with a Cobra license tag. The car was written up in the Winter 65/66 edition of "Style Quarterly" magazine. Shelby American internal production records show that the car was shipped to Shelby American for evaluation and review. AC Cars Ltd internal production records show that Shelby American placed an order for two 96-inch chassis (CSX 5001–5002) in 1966. AC labeled these chassis as "GHIA CONVERTIBLE" in their factory ledger.
FORD XD COBRA
(CSX 3001)
Shelby American internal production records show that the car was shipped to Shelby American for evaluation and review in early 1966. The vehicle was returned to Ford and now resides in the Detroit Historical Museum.
AutoKraft Autokraft manufactured an AC 289 continuation car called the Autokraft Mk IV, basically a Mk III with a Ford V8 and Borg Warner T5 Transmission. The Mk IV also received an independent suspension.
In 1986, Autokraft (as a joint venture with Ford joining in 1987) purchased AC Cars, and produced the AC Mk IV Cobra, with a at 4,200 rpm, Ford V8, which provided a top speed of and in 5.2 seconds.