I mostly dismantled the engine out of CSX2551 this morning. This is the engine with Shelby number 00026. Some details are
Block
C4OE-6015F cast 4F4 with 4H25B stamped on oil pan rail and nothing stamped in front of left cylinder head. There is a pressed in plug in the forward lifter valley wall passage towards the timing cover oil fill location of early engines. (I don’t know if the block decks were milled but the heads on the engine were.)
Harmonic Balancer
C3OE B hub with outer ring dated G4
Timing Cover
C4OE-6059A 64 eight raised dots (no boss on cover where earlier engines had an oil fill)
Comparing blocks numbered 00004 and 00026 this morning they share these features
1 – The pan rails of both are stamped 4H25B.
2 – Neither block has an assembly date showing (could have been milled off) in front of the left cylinder head.
3 – Both blocks have a pressed in plug in the forward right hand corner of the lifter valley.
4 – BOTH BLOCKS ARE REPAIRED! Under the accumulated crud I found that both blocks had been repaired at some time in their past. 0004 had the right front tooling boss broken off and welded back on with some type bright colored alloy. 00026 had some type defect at the oil pressure sender extension boss that was welded up with some type bright alloy.