Thread: I need some help IDing with this motor

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John your block is a 72/Nov/8th casting. The lack of a casting number and the vertical ribs was very common for 72 truck and service replacement blocks. At some point the C4AE-B crank was added. It could have modified for the 4.00 stroke if your certain it is that. Or you might have measured wrong and it's a 3.78 stroke. Either way for sure the crank has a 390/427 casting number. The C4-B crank was used in 390 HP, HD and PI applications besides the 427. IU, IUB and IUA are factory 428 3.984 crank numbers. You can use almost any combination of FE/FT blocks and cranks and have them interchange. What number is on the connecting rods? I'd also triple check that crank stroke. If someone has taken the time to stroke that crank to 4.00" it could be worth a pretty penny. No biggie on the heads. C8-H heads later evolved into the D2-AA heads. They are the same casting just different numbers. The C8 a 68 and later, the D2 72 and later. Same chamber and valve size. The D2-AA having hardened seats from the factory. C8-H did not.


G.