1968 Ford Mustang Fastback – 428 Super Cobra Jet (4 Speed) !!

Ford rated the 428 Cobra Jet at 335 horsepower, but real-world output landed closer to 400, a gap that let the mid-year engine option dominate NHRA’s Super Stock class within months of its release. Fewer than 1,300 GT Fastbacks were built with the Cobra Jet in 1968, each carrying an R engine code that collectors still chase today. This surviving example shows just how understated the factory kept its most dangerous engine option.

Wow actually seeing one of these bad boys, in this condition is amazing.

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Ford’s own paperwork said 335 horsepower, but nobody who actually raced a 428 Cobra Jet believed the number on the window sticker. Real-world dyno pulls put the engine closer to 400 horses, a gap wide enough that Ford’s rivals didn’t see it coming until it was already beating them at the strip. The Cobra Jet didn’t even exist when the 1968 Mustang lineup launched, it arrived mid-year, on April 1st, as Ford’s answer to big-block Camaros, Firebirds, and 340-powered Darts and Cudas that had been embarrassing Mustangs on the street. Underneath a deceptively subtle black hood scoop and stripe sat 427-style cylinder heads, a race-bred intake manifold, and a torque figure, 440 lb-ft, that turned ordinary street driving into an event. Fewer than 1,300 GT Fastbacks were built with this engine that year, each one carrying an R in its VIN code that gearheads still hunt for today. How does a mid-year engine option end up dominating an entire NHRA class in its first season?

The Engine That Arrived Four Months Late

The 428 Cobra Jet wasn’t part of the 1968 Mustang lineup when the model year launched, Ford introduced it mid-year, on April 1st, as a direct response to big-block Camaros and Firebirds, along with 340-powered Darts and Barracudas, that had been outrunning Mustangs on the street. Under the deceptively subtle black hood scoop and stripe sat 427-style cylinder heads, a race-derived intake manifold, genuine ram-air induction, and a Holley 735-CFM four-barrel carburetor feeding it all.

Sandbagged on Paper, Dominant at the Strip

Ford’s own literature rated the Cobra Jet conservatively at 335 horsepower, but real-world dyno figures landed closer to 400, backed by a genuinely brutal 440 pound-feet of torque. That underrating didn’t stop the engine from making an immediate statement: a factory team of eight specially prepared Cobra Jet Mustangs ran 11.5-second quarter miles at 120 mph to sweep the Super Stock class at the 1968 NHRA Winternationals, with driver Al Joniec winning in one of just 50 lightweight Cobra Jets built specifically for racing that year. Fewer than 1,300 GT Fastbacks total received the Cobra Jet in 1968, each one carrying an R engine code in its VIN.

That combination of factory rarity and race-proven performance is exactly why R-code 1968 Mustangs remain some of the most sought-after Fastbacks from the entire muscle car era.

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