The Ford V-8 Engine Workshop
428 Cobra Jet

428 CJ with shaker hood Cobra on wheels
'69 Mustang
428 Cobra Jet
The 428 Cobra Jet, introduced April 1968, was a high torque, quiet, inexpensively built engine. Not intended for true racing durability, it lacked the bottom end features of the side-oiler 427. Missing were the cross-bolted main bearing caps and oiling improvements. The thin cylinder walls of the 427's 4.23" bore made normal assembly line production impossible. The smaller bore of the 428 was well within normal production line capabilites. The longer stroke (3.98 vs. 3.78 for the 427) gave the engine powerful low-end punch.

FE block normal main bearing web FE block triple main bearing web
The 428 CJ and SCJ blocks (right hand picture) have extra main bearing webbing and thicker main caps than the normal 390 or 428 (left hand picture).

Connecting rods are similar to those used in the 390 GT, but CJ and Police Interceptor engines are fitted with 13/32" bolts.

Unlike other FE family engines, the 428 is externally balanced. Due to different piston and connecting rod weights, there are actually four different 428 crankshafts. One used for normal 428, 428 Police Intercepter, and 428 CJ before 12/26/69. One for 428 CJ after that date, and two for 428 Super Cobra Jet before and after that date.

The 428 CJ cylinder heads feature an unmachined chamber of 73-76cc, 2.06" intake valves and 1.66" exhaust valves. The intake ports measure 1.34" x 2.34". Exhaust ports measure 1.28" x 1.84". The 16-bolt pattern exhaust face is unique to these CJ heads. A 735 cfm Holley carburetor sits on a cast iron intake manifold. Curiously, the 428 Police Interceptor got an aluminum intake. Dished pistons with valve reliefs result in 10.6:1 compression. A thermactor air injection system was required to meet federal emissions standards. Special free flowing cast iron exhaust manifolds were fitted. These are similar to those used on 427 Galaxies. The Q-code CJ was rated at 335 BHP @ 5600 RPM, obvisously under rated.

The Super Cobra Jet, available only with a 3.91 or 4.30 rear axle ratio, included additional features. For improved high speed reliability, the SCJ used the beefier LeMans style capscrew connecting rods and forged pistons. This heavier reciprocating assembly required additional balance mass on the crankshaft added via a special front oil seal sleeve with a cast-on counterweight. An engine oil cooler forced the horns to both be located on one side of the car. There is a reinforcement plate for the horn bolts behind the raditor core support -- often lost, and missing from fakes. Air conditioning was not available as the oil cooler used up the space in front of the radiator. SCJ engines use 427 Le Mans style rods with capscrews and forged pistons.

On R-code cars, a Ram Air option was installed. This was in the form a scoop mounted atop, and part of, the air cleaner assembly. This went through a square foot hole in the hood. The alignment of the scoop in relation to the air cleaner and the opening in the hood was adjustable. The now famous term "shaker hood scoop" fits appropriately, especially when the engine features a more agressive camshaft profile.

1968/70 428 CJ Head
casting number C8OE-6090-N

These cylinder heads are found on the 1968/70 428 CJ and SCJ engines. The 16-bolt pattern exhaust face is unique to these CJ heads. 427 Low Riser heads are similar, but have a 14-bolt exhaust face.
428 CJ cylinder head intake face

428 CJ cylinder head exhaust face

428 CJ cylinder head combustion chambers

428 CJ cylinder head valve springs

428 CJ Exhaust Manifolds

These exhaust manifolds are found on 428 CJ regardless of body style. The passenger side manifold (the larger one shown at the top) is casting # C8OE-9431-B. The drivers side manifold shown here is fitting to late 1969 and 1970 cars, casting # C9OE-9430-D.
428 CJ Exhaust Manifold