In 1965, Shelby American fitted 51 AC Cobras with Ford 427 engines, intending to race the car model in that year’s International Automobile Federation manufacturers championship series. When the car, known at the time as the Cobra Mark III or the big-block Cobra, failed to achieve homologation status due to low production numbers, some examples were sold to privateer racers and the rest were detuned for street use. The road car became known as the Cobra S/C, for “semi-competition” or, some say, “street compet…