Classic Mustang: The 428 Cobra Jet and The Boss

Classic Car Parts Co.

1968 428 Cobra Jet Classic Mustang

The 1968 Ford Classic Mustang received a limited number of 427 engines that were slipped into the engine bays, along with a simpler grille and side trim. These 427 engines were marginally detuned but still cranked out 390bhp, enough to strike fear on the streets. On April 1, 1968, Ford unveiled its most famous line of engines, the 428 Cobra Jet. It was based on the regular 428 but with larger valve heads, the race 427's intake manifold, and an oil-pan windage tray. It had ram-air induction and breathed through a functional hood scoop, using the now famous “shaker hood”. The engine was listed at 335bhp but was rumored to be over 400bhp. The Shelby's were still available, joined by an available convertible model; they will be renamed as the Shelby Cobra. The GT-350 replaced its 289 cid 306 bhp engine with the 302 cid 250 bhp engines. The GT-500 was dropped half way through the model year and was replaced by the GT-500KR ("King of the Road"). The GT-500KR came with the Ram Air 428 Cobra Jet, still rated at 335 bhp.

1969 Boss Classic Mustang

Originally the Boss series of Mustangs would be mainly for the circle tracks, they were built to qualify the 429 V8 for NASCAR. The package for Boss 429 included a race ready 429 cid V8 with ram air induction, an aluminum high riser and header type exhaust manifolds. The Boss series would be equipped with only a four speed manual transmission and a 3.91:1 Traction-Lok axle. Also with an oil cooler, trunk mounted battery, race suspension, and the highest quality interior Mustang had to offer. Very impressive on paper, the Boss 429s failed on the street where their dependence on high revs hurt their street starts and the initial batch had incorrect valve springs that would stop winding at 4500rpm instead of 6000rpm. Nevertheless, it had good handling and would last through 1970. . To compete with Chevrolet's Camaro Z/28 in Trans Am racing, the 429 would be replaced with the 302 ci V8, the package would include heads from the 351 ci race engine and the largest carb Ford made. The 302 would be under rated as were the Camaro Z/28 at 290bhp, for the street the Boss 302 had the “Shaker Hood” scoop option. Meanwhile Shelby Mustangs would become more luxurious with a price to match.