Ford Mustang 428 Cobra Jet
The 428 Cobra Jet engine was Ford's response to growing demand for more power in the muscle car wars. Introduced mid-1968, the CJ combined the robust bottom end of the 428 Police Interceptor engine with improved cylinder heads featuring larger ports and valves, a more aggressive camshaft, and a larger Holley carburetor.
Ford officially rated the Cobra Jet at a conservative 335 horsepower — a figure widely regarded as one of the great understatements in muscle car history. Independent dyno testing consistently showed output closer to 400-410 horsepower, and the engine's prodigious torque (well over 400 lb-ft) made it devastating off the line.
The Cobra Jet's dominance on the quarter-mile was immediate and emphatic. At the 1968 NHRA Winternationals, Hubert Platt drove a CJ Mustang to a Stock Eliminator victory, running mid-11s in near-stock trim. The result sent shockwaves through the muscle car world and validated Ford's big-block Mustang as a serious threat.
The Ram Air version added a functional hood scoop that directed cold air to the carburetor, providing a modest power increase at speed. The Shaker scoop, which protruded through the hood and was mounted directly to the engine, became one of the most iconic visual features of the muscle car era — literally shaking with each rev of the engine.
The Super Cobra Jet (SCJ) option added forged pistons, stronger 'Le Mans' connecting rods, an external oil cooler, a 4.30:1 rear axle ratio, and a Detroit Locker limited-slip differential. The SCJ was designed for sustained high-RPM operation and drag racing abuse.
The 428 Cobra Jet Mustang represents the peak of the brute-force approach to performance. In an era when engineers simply kept making engines bigger and more powerful, the CJ was among the mightiest. Its place in muscle car history is secured by its racing victories, its cultural significance, and the sheer visceral thrill of 428 cubic inches at full song.
428 CJ cars are identified by the Q-code VIN. The SCJ (R-code with Drag Pack) is rarer and significantly more valuable. Key authentication points include the correct Holley carburetor casting number, CJ-specific exhaust manifolds, and the correct distributors. Many 390 cars have been converted to CJ specification — VIN verification is essential. The Ram Air and Shaker scoop options add value. SCJ cars with the Detroit Locker and 4.30 gears are the holy grails. Inspect for the usual big-block Mustang issues: stressed front end, nose-heavy handling, and cooling system adequacy.
The 428 CJ was introduced mid-year 1968. It was available in SportsRoof, Hardtop, and Convertible body styles, as well as in the Mach 1 package. Exact CJ production numbers are difficult to determine as Ford tracked engine codes, not complete car configurations. The SCJ was a Drag Pack option that added approximately $155 to the price.