Datum point for squaring up a block

[Circlotron]

Say you want to square up an engine block so that the deck surface, main bearing axis, cam axis, lifter bores etc are all in proper alignment with one another. Which one do you select as the reference to line the others up to? If they are all out a bit, what do you do?

[F-BIRD'88]

Check your bank account balance.

[mt-engines]

Crank centerline, then deck height and angle is achieved at your a A axis.

If they are all out a bit you correct it by removing material

[modok]

The decks can usually be squared to the crank no problem,
and cylinders can be bored 90 to the crank, because they usually are anyway to start from the OEMs.

BUT.... head bolt holes are already drilled and the casting is only however thick it is, so often it is not wise to move the cylinders more than .010" without checking the casting thickness and gasket location.

The crank often cannot be moved more than a few thou before the alignment of the transmission, shaft seals, or timing gears may need to be checked.

And the cam...... lets be honest most aren't checking the lifter bores.
The location of the camshaft in the engine is FAR less important than the location and angle of the lifter bores relative TO the cam.