About AC Cobra

Like many British specialist manufacturers, AC Cars had been using the smooth, refined Bristol straight-6 engine in its small-volume production, including its AC Ace 2-seater roadster. This had a hand built body with a steel tube frame, and aluminium 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. Bristol decided in 1961 to cease production of its engine and instead to use Chrysler 331 cid (5.1 L) V8 engines. Although untrue, it is commonly believed that AC was left without a future source of power and that American ex-racing driver Carroll Shelby saved the company from bankruptcy. AC started using the 2.6 litre Ford Zephyr engine in its cars. In September 1961, 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. He first went to Chevrolet to see if they would provide him with engines, but not wanting to add competition to the Corvette they said no. Ford however, wanted a car that could compete with the Corvette and they happened to have a brand new thin-wall small-block engine which could be used in this endeavor. It was Ford's 260 in³ HiPo (4.2 L) engine - a new lightweight, thin-wall cast small-block V8 tuned for high performance. In January 1962 mechanics at AC Cars in Thames Ditton, Surrey fitted the prototype chassis CSX0001 with a 221ci Ford V8. 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.[1] His team fitted it with an engine and transmission in less than eight hours and began road-testing.

Production proved to be easy, since AC had already made most of the modifications needed for the small-block V8 when they installed the 2.6 litre Ford Zephyr engine, including the extensive rework of the AC Ace's front end. The most important modification was the fitting of a stronger rear differential to handle the increased engine power. A Salisbury 4HU unit with inboard disk brakes to reduce unsprung weight was chosen instead of the old ENV unit. It was the same unit used on the Jaguar E-Type. On the production version, the inboard brakes were moved outboard to reduce cost. 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 motor.

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The first 75 Cobra Mark I (including the prototype) were fitted with the 260 engine (4.2 L). The remaining 51 Mark I model were fitted with a larger version of the Windsor Ford engine, the 289 in³ (4.7 L) V8. In late 1962 Alan Turner, AC's chief engineer completed a major design change of the car's front end and was able to fit it with rack and pinion steering while still using transverse leaf spring suspension. 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 to the summer of 1965 (the last US-bound Mark II was produced in November 1964).

By 1963 the leaf-spring Cobra was losing its supremacy in racing. Shelby tried fitting a larger Ford FE engine of 390 in³. Ken Miles drove and raced the FE-powered Mark II and pronounced the car was virtually undrivable, naming it "The Turd." A new chassis was developed and designated Mark III.

The new car was designed in cooperation with Ford in Detroit. A new chassis was built using 4" main chassis tubes (up from 3") and coil spring suspension all around. The new car also had wide fenders and a larger radiator opening. It was powered by the "side oiler" Ford 427 engine (7.0 L) rated at 425 bhp (317 kW), which provided a top speed of 163 mph (262 km/h) in the standard model and 485 bhp (362 kW) with a top speed of 180 mph (290 km/h) in the competition model. 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 finished in Shelby's workshop. Although an impressive automobile, the car was a financial failure and did not sell well. In fact to save cost, most AC Cobra 427's were actually fitted with Ford's 428 in³ (7.0 L) engine, a long stroke, smaller bore, lower cost engine, intended for road use rather than racing. It seems that a total of 300 Mark III cars were sent to Shelby in the USA during the years 1965 and 1966, including the competition version. 27 small block narrow fender version which were referred to as the AC 289 were sold in Europe. Unfortunately, The MK III missed homologation for the 1965 racing season and was not raced by the Shelby team. However, it was raced successfully by many privaters and went on to win races all the way into the 70's. Interestingly, 31 unsold competition cars were detuned and made road worthy and called S/C for semi-competition. Today, these are the rarest and the most valuable models and can sell for in excess of 1.5 million dollars.

The AC 427 (i.e. the Mark III) dimensions were: overall length of 14.583 feet (4.445 m), overall width of 5.583 ft (1.702 m), height (with its removable top in place) of 4.250 ft (1.295 m), turning circle of 34 ft (10.363 m), wheelbase of 8.00 feet (2.438 m), front track of 4.50 ft (1.372 m) and rear track of 4.417 ft (1.346 m). Its fuel tank held 18 imperial gallons and its empty weight was approximately 2,300 lb (1044 kg).[2]

AC Cobras had an extensive racing career. Shelby wanted it to be a "Corvette-Beater" and at nearly 500 lb (227 kg) less than the Chevrolet Corvette, the lightweight car did just that. The Cobra was perhaps too successful as a performance car and reputedly contributed to the implementation of national speed limits in the United Kingdom. An AC Cobra Coupe was calculated to have done 185 mph (298 km/h) on the M1 motorway in 1964, driven by Jack Sears and Peter Bolton during shakedown tests prior to that year's Le Mans 24h race.[3] However, government officials have cited the increasing accident death rate in the early 1960s as the principal motivation, with the exploits of the AC Cars team merely highlighting the risk.

Although successful in racing, the AC Cobra was a financial failure, which led Ford and Carroll Shelby to discontinue importing cars from England in 1967. AC Cars kept producing the coil spring AC Roadster with narrow fenders, a small block Ford 289 and called the car the AC 289, it was built and sold in Europe until late 1969. This car with modifications would appear again in 1982 as the Autokraft MkIV, basically an AC MkIII car with a 5.0L Ford V8 and Borg Warner T5 Transmission. AC also produced the AC Frua until 1973. The AC Frua was built on a stretched Cobra 427 MK III coil spring chassis using a very angular handsome steel body designed and built by Pietro Frua. With the demise of the Frua, AC went on building lesser cars and eventually fell into bankruptcy in the late 1970s'. The company's tooling and eventually the right to use the name, were licensed by Autocraft, a Cobra parts reseller and replica car manufacturer owned by Brian A. Angliss. Autocraft was manufacturing an AC 289 continuation car called the Mark IV. Shortly thereafter, Carroll Shelby filed suit against AC Cars and Brian A. Angliss, in U.S. District Court in Los Angeles. The ensuing settlement resulted in Shelby and AC Cars/Angliss releasing a joint press release whereby AC/Angliss acknowledged that Carroll Shelby was (and is) the manufacturer of record of all the 1960s AC Cobra automobiles in the United States and that Shelby himself is the sole person allowed to call his car a Cobra. Despite this there is no doubt that every Cobra made in the '60s was manufactured by AC Cars in England, shipped to Shelby for completion. Carroll Shelby's company Shelby Automobiles, Inc. continues to manufacture the Shelby Cobra FIA 289 and 427 S/C vehicles in various forms at its facility in Las Vegas, Nevada. These cars retain the general style and appearance of their original 1960s ancestors, but are fitted with modern amenities. In 2006 Carol Shelby's own Shelby Cobra sold at an auction in Arizona for £2.8million.[4]