Markings on block

Took the head of my F-head to change the head gasket. At each bore there is a letter stamped on the top of the block. Front to back they are stamped D-D-C-D. #2 the D is stamped sideways. Any idea what these might mean?

 

Into the deck? Really? I'd think that would be a very bad idea. Stamping raises the metal around the letters... the deck is supposed to be perfectly flat, for good sealing.

 

1960, 22,000 miles. Bought it from original owner. Never had it apart.

 

•C: 0.002" undersized piston pin
•D: 0.010" undersized main bearing journals

from 3B page http://www.film.queensu.ca/cj3b/Hurricane.html

 

That same article indicates that the letters would be stamped after the engine serial number, not on the deck of the block. One would think they would undersize all of the main journals and piston pins, not just in individual cylinders.

 

the 3B pages are getting updated all the time

if you look at all the engine serial # recorded in their database ( link below) only A, B and E are found , so
C and D may have been stamped into block during assembly

i have seen pictures of other blocks stamped in what looked like the valve path - no gasket covering,
unlike this one which appears to be on outter edge
http://www.film.queensu.ca/cj3b/serialnos/SerialNosEngine.html