MustangMike
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Unfortunately, the 428 PI motors (just the same as T-Bird and GT-500 428s) have 390 heads on them, and were designed for torque, not high RPM power. The 390 heads have smaller combustion chambers and valves than the 428 CJ and use different pistons. Only the KR version of the GT-500 had real CJ heads.
428 CJ and 427 low riser heads have the next size larger combustion chambers (over the 390) and 427 Medium Riser and High Riser Heads have larger combustion chambers and valves than that.
The 428 CJ head was developed by Tasca Ford. They wanted to put 427 Medium Riser heads on the 428, but the bore is not large enough to clear the larger valves. A 428 CJ head has 427 low riser valves and combustion chambers with 427 Medium Riser ports. It worked very well, and Ford built some late year 68 Mustangs with the 428 CJ motor, and they won the NHRA Winter Nationals that year with them.
390, 406 and 427 all have the same stroke, just the bore size changes (4.05; 4.13; 4.23). A 427 Ford is really 425 CI. 410 and 428 engines have longer strokes. A 428 crank in a 427 block is 447 CI. A 360 is a 352 crank in a 390 block, and a 406 is a 390 crank in a 428 block.
390s were one of my favorite engines, very durable, plentiful and capable of producing real power. 428 and 410 engines were externally balanced and not so durable. The 390 GT motor had the same hydraulic cam as a 428 CJ. Unfortunately, in the 67-69 Mustangs, the pathetic exhaust manifolds and transverse mufflers killed their performance. If you put headers and real dual exhaust on them, they came alive. Add a 800 double pumper Holley, Electronic Ignition and Aluminum intake and you had a screamer! (I also put a 427 Ford solid lifter cam in my 68). It was very fast and easily took out built 440 6 pack Super Bees, etc.
428 CJ and 427 low riser heads have the next size larger combustion chambers (over the 390) and 427 Medium Riser and High Riser Heads have larger combustion chambers and valves than that.
The 428 CJ head was developed by Tasca Ford. They wanted to put 427 Medium Riser heads on the 428, but the bore is not large enough to clear the larger valves. A 428 CJ head has 427 low riser valves and combustion chambers with 427 Medium Riser ports. It worked very well, and Ford built some late year 68 Mustangs with the 428 CJ motor, and they won the NHRA Winter Nationals that year with them.
390, 406 and 427 all have the same stroke, just the bore size changes (4.05; 4.13; 4.23). A 427 Ford is really 425 CI. 410 and 428 engines have longer strokes. A 428 crank in a 427 block is 447 CI. A 360 is a 352 crank in a 390 block, and a 406 is a 390 crank in a 428 block.
390s were one of my favorite engines, very durable, plentiful and capable of producing real power. 428 and 410 engines were externally balanced and not so durable. The 390 GT motor had the same hydraulic cam as a 428 CJ. Unfortunately, in the 67-69 Mustangs, the pathetic exhaust manifolds and transverse mufflers killed their performance. If you put headers and real dual exhaust on them, they came alive. Add a 800 double pumper Holley, Electronic Ignition and Aluminum intake and you had a screamer! (I also put a 427 Ford solid lifter cam in my 68). It was very fast and easily took out built 440 6 pack Super Bees, etc.
