How Shelby Works

The 1964 Shelby AC Cobra was one of Carroll Shelby’s first American masterpieces.

When heart trouble forced Carroll Shelby to retire from driving race cars after he won the LeMans 24 Hours in 1959, the one-time Texas chicken rancher turned to building stark, incredibly fast road cars to suit himself and other like-minded enthusiasts. The first were the legendary Shelby-Cobras.

Starting with lithe, lightweight Ace roadsters from A.C. Cars in England, Carroll replaced a plodding small six-cylinder engine with potent Ford V-8s: initially 260- and 289-cubic-inch engines with up to 306 horsepower, then mammoth 427s making up to 425 bhp. The result was a hairy thrill on the road and nearly unbeatable in major-league sports-car racing.

Even the "little" 289 could scale 0-60 mph in 5.5 seconds and exceed 135 mph. The otherworldly 427s needed just 4.2 seconds 0-60 on the way to 165 mph.

Shelby built 654 small-block Cobras and some 350 big-block versions from 1962 to '68. All have since become prized collector's items fetching six-figure prices (sometimes more), thanks to a fabled competition record (seven U.S. national road-racing championships, the World Manufacturer's title in 1965) and a raw, elemental nature unmatched by other sports cars.

Those same factors explain the numerous Cobra "replicars" that appeared after them and which Shelby fiercely fought against. Shelby also contributed to the mid-engine GT40 and Mark IV prototypes that took Ford to the racing pinnacle by winning the 24 Hours of LeMans in 1966-69.

Equally famous, but more popular and practical, was the series of limited-edition Shelby Mustang GTs built in 1965-69. The first, named GT 350 for no particular reason, was a race-inspired conversion of Ford's new 1965-66 "ponycar" carried out by the small Shelby American shop in Los Angeles. Early Shelby Mustangs were uncompromising grand tourers equally at home on the track. Post-1967 models were planned and built by Ford and were thus "softer," though still plenty exciting.

Ford Division chief Lee Iacocca had asked Shelby to modify the Mustang so it could win the Sports Car Club of America's national B-production championship. The GT 350 did just that in 1965-67, virtually running away from the field to give showroom Mustangs a "competition-proved" aura.

The 1965-66 GT 350 began as a white, blue-striped Mustang fastback supplied with the excellent small-block 289 in 271-bhp "Hi-Performance" guise. "Hi-rise" manifold, bigger four-barrel carburetor, free-flow exhaust, and other Shelby changes lifted output to 306 bhp at 6000 rpm. Carroll also specified the Mustang's optional Borg-Warner T-10 four-speed gearbox, plus a stronger rear axle from the full-size Ford Galaxie to replace the stock Mustang's Falcon unit.

Other component swaps included Koni adjustable shocks, Shelby-cast 15-inch alloy wheels wearing high-performance Goodyear tires, metallic friction surfaces for both rear-drum and front-disc brakes, and fast-ratio steering (with relocated front suspension mounting points). A hefty steel tube linked the tops of the front shock towers to reduce body flex in hard cornering.

The result of all this was near-neutral handling instead of the stock Mustang's strong understeer, plus 0-60 mph acceleration of just 6.8 seconds -- impressive even today -- and over 120 mph all-out. An optional Paxton supercharger, offered during 1966, boosted horsepower beyond 400 and cut the 0-60 time to just five seconds. Shelby built only such 11 cars, though a handful of stock GT 350s received owner-installed "blower" kits.

For more on the amazing Shelby cars, old and new, see: