Of all the Cobra variants the 427 Semi/Competition or S/C is the most desirable series. Built from Shelby's competition production line, these were purposeful race-cars that were prepared at the last minute for the road.
The story of the Cobra begins as early as 1959 when Carol Shelby raced for Aston Martin, winning the 24 Hours of Le Mans. Along the way he probably took notice of a well performing AC Ace that would become a foundation for his next venture.
After quitting racing, he return to America to build his own sportscar, turning to Charles Hurlock of AC Cars to supply a chassis and body that was suitable for the new 260 cubic inch Ford V8. After considerable racing success, Ford provided the even larger 427 FE engine. By 1965, chief engineer Ken Miles wanted to fit thengine to win SCCA’s A Production Class and stay ahead of the Corvette Grand Sport.
The Ford 427 was actually a 425 cubic inch V8 developed for the 427 NASCAR regulations. These were strictly race engines with solid lifters and became know for their side oil passage that sent oil to crank first before the valvetrain. Somewhere around 400 bhp was realized.
With assistance from Ford and AC Cars, the team at Shelby American modified the existing AC chassis design to accommodate the big block engine. The completed design was called the mark III chassis was manufactured with larger and wider spaced chassis rails. Shelby ordered 100 of these from AC Cars.
Due to the weight of the engine the brakes and suspension were also upgraded. The body was featured prominent wheel arches to fit wider magnesium wheels and tires. Competition features included an oil cooler, side exhausts, large fuel filler, 42-gallon fuel tank, front jacking points and a roll bar.
Naturally, the 427 Cobra was expected to compete at the top level of motorsport and abroad. Shelby went into immediate production, finishing just over 50 cars when bad news struck. The FIA visited and was unsatisfied with the minimum number of cars required to homologate the 427 in the World Sports Car Championship. Needing 100 cars or more, Shelby's market to was immediately slashed, he cancelled his order with AC, but still had 53 big block Cobras nearly completed.
Naturally some of these cars were sold in primer to American teams and drivers but 34 chassis were still without a home. Shelby’s east coast representative, Charles Beidler, suggested they paint the remaining cars and offer them as the fastest street car in the world.
Not soon after Shelby started fitting the cars with production windscreens. Out of 53 Cobras, CSX3001 through CSX3053, three were sent to Ford, 19 were sold for competition and the rest were converted for road use.
On the road, the S/C was a radical machine. Sports Car Graphic magazine editor Jerry Titus reached 0-100 mph in 13.2 seconds. By comparison the nearest Aston Martin of the day was barely capable of less then twenty seconds.
Due to the very limited production, original S/Cs are a rare sight. Only Shelby's personal Super Snake was faster, using twin turbochargers to offer 800 bhp.
