Test Driving 1967 Shelby GT500 390 V8 Mustang

Ford advertised the 1967 Shelby GT500 at 355 horsepower, and almost nobody in the industry believed the figure. The engine underneath was never supposed to be there at all, and the number on the spec sheet was arguably the least honest thing Ford printed that year. Only 2,048 were built, in the last season Shelby American assembled the cars entirely in California. Read on for what Ford was really hiding behind that rating.

Ford’s own paperwork said 355 horsepower. Almost nobody in the industry believed it, and the people who actually drove the car believed it least of all. Under the long hood of the 1967 Shelby GT500 sat an engine Ford had originally developed for police cruisers, fed by two Holley four-barrels mounted backward on an aluminum mid-rise intake and tied together by a progressive linkage complicated enough to intimidate most home mechanics. Carroll Shelby had looked at the standard 390 GT big block, decided it lacked the drama a car wearing his name deserved, and gone hunting through Ford’s inventory for something considerably meaner. What he found, and what Ford chose to advertise it as, turned out to be two very different stories.

The 390 in the Title Is Not the Engine in the Car

The title on this one is a little misleading, and the confusion is worth clearing up because it trips up buyers to this day. Ford’s big-block option in a standard 1967 Mustang GT was the 390 cubic inch FE, a torquey but fundamentally ordinary engine rated at 320 horsepower. That is the 390 people remember from Mustang order sheets. The GT500 did not use it. Shelby American went instead to the 428 cubic inch member of the same FE family, a physically similar but substantially larger displacement engine, and it is the 428 that defines the car. Any 1967 Shelby GT500 wearing a genuine drivetrain has a 428 under the hood, not a 390, and the distinction is the single most important thing to verify before money changes hands.

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Why Shelby Went Shopping in Ford’s Police Parts Bin

The 428 Shelby chose carried the Police Interceptor designation, meaning it came from the side of Ford’s catalog built for sustained high-speed pursuit duty rather than for quarter-mile heroics. Shelby American topped it with an aluminum mid-rise intake manifold carrying a pair of 600 CFM Holley four-barrels arranged in a progressive setup, so the front carburetor handled ordinary driving while the second opened only when the driver asked for everything. It was a deliberately theatrical piece of engineering. Open the hood at a cruise night and the twin Holleys, the finned aluminum, and the cast Cobra lettering did as much for the car’s reputation as anything happening at the rear tires.

The Horsepower Number Nobody in Detroit Believed

Officially the package was rated at 355 horsepower at 5,400 rpm and 420 lb-ft of torque at 3,200 rpm. Almost no one takes those figures at face value. Period testers and modern engine builders alike put real output closer to 400 horsepower, and the gap is generally understood to have been deliberate. Insurance companies in 1967 were already surcharging young buyers on advertised horsepower alone, and a conservative rating kept a GT500 marginally more affordable to insure than its performance deserved. Detroit sandbagged ratings across the board in this era, in both directions depending on what suited the marketing department, but few engines wear the reputation as comfortably as the GT500’s 428.

What Shelby Actually Changed Beyond the Engine

The engine was only part of what separated a GT500 from a well-optioned Mustang. Shelby American fitted a fiberglass nose that stretched the car three inches further forward, functional hood scoops, brake cooling ducts in the lower rear quarters, and a fiberglass decklid with an integrated spoiler. Inside went a roll bar with inertia-reel shoulder harnesses, a wood-rimmed steering wheel, and an auxiliary gauge pod on the console. The 1967 cars were also the first Shelbys with high-mounted driving lamps in the grille, an arrangement that had to be moved apart in some states because of laws governing minimum spacing between forward-facing lights.

Torque Where the GT350 Had Revs

Driving one makes the difference between the two Shelby models obvious within a block. The GT350, running Ford’s 289 small block, wants revs and rewards a driver willing to work the gearbox. The GT500 does almost the opposite. The 428 delivers a wall of low and midrange torque, pulls the car forward from barely off idle, and makes third gear useful in situations where a GT350 driver would still be reaching for second. The tradeoff is nose weight. The big FE sits heavy over the front wheels, and the car understeers more readily than the small-block cars do, which is exactly why the GT500 has always been described as a grand tourer where the GT350 is described as a race car with plates.

2,048 Cars and the End of an Era in Los Angeles

Shelby American built 2,048 GT500s for 1967 alongside 1,175 GT350s, and that season carried extra weight in the company’s history. It was the last model year the cars were assembled in-house at the Shelby operation in Los Angeles before Ford moved production of the 1968 cars east to a contractor in Michigan. Everything after that point is a Shelby by badge and by design intent, but the 1967 cars are the last ones physically built by Shelby’s own people in California. That fact alone puts a premium on 1967 examples that no amount of restoration quality can manufacture for a later car.

What Owners Fight With Fifty Years Later

Owning one is not without friction. That progressive dual-quad linkage is the part restorers complain about most, since correct components are scarce and a poorly adjusted setup will either bog on transition or run both carburetors wide open far too early. Cooling is the other perennial fight, because a 428 packed into an engine bay designed around a small block generates more heat than the original radiator was ever asked to shed in traffic. Correct date-coded parts, from the intake to the carburetors to the exhaust manifolds, carry serious money on their own, which is one reason so many cars on the market wear replacement components that look right but do not date correctly.

Why the GT500 Still Leads the Shelby Market

All of that feeds directly into why the GT500 sits where it does in the market. Values for documented, numbers-matching 1967 cars have consistently run well ahead of comparable GT350s, driven by the combination of low production, the last-year-in-California story, and an engine whose reputation has only grown as its advertised rating has become less believable with time. Registry documentation, a matching engine, and a clear ownership history separate the genuine cars from the well-executed clones that have followed the model for decades. For a car Ford deliberately undersold on paper, the market has spent fifty years correcting the record.

The GT500KR Picked Up Where This Car Left Off

The story does not end with the 1967 car. For 1968, Ford introduced the GT500KR, short for “King of the Road,” replacing the earlier engine with the newly developed 428 Cobra Jet, an engine that had just proven itself on the drag strip and briefly held its own against cars from Chrysler and Chevrolet running considerably larger displacement. That same year, Ford also moved GT500 assembly out of Shelby’s own Los Angeles operation and into a contracted plant in Michigan, closing the chapter this 1967 car represents. Enthusiasts still debate which model deserves more credit: the 1967 car for establishing the GT500 as a genuine grand tourer, or the 1968 KR for delivering an engine that finally matched the theatrical claims Shelby had been making about power all along. What is not in dispute is that 1967 was the last year the GT500 name was attached to a car built entirely under Shelby’s own roof, which is precisely why collectors treat it as a distinct and separately valued chapter in the model’s short history.

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