R dont know
273 Cubic inches
8-5. My guess is Aug of 1965 assembly date
My feb of 67 built dart has an engine assembly C273 12-6 (december 1966)
By all accounts the C of C273 = model year 1967 273
There is also a B which might mean 0.010 undersized main and crank jurnals
and 319 stamped into the area as well unknown meaning, posabily from a rebuild?
Look towards end of post
How to ID a Small Block Engine Block:
