CJ-3A
Engine Casting & Serial Numbers
Casting Numbers
All CJ-3A engine blocks should have the following casting
number located on the lower right hand side of the engine block:
641087-L-W11-A-NI-CR-N2
It's important to note that not all casting numbers are the
same. The first number, 641087 is common to all CJ-3A engine blocks.
I have seen two versions of the casting numbers with "W11" and "W12." The
theory is that this is the forge or cast number.
NI is Nickel and CR is Chrome. These two metals
are used to give the Iron in the casting alloy properties so it can expand and
contract and be machined to function as an engine block. Back in the early days
of the automobile many inferior engines were produced because they did not have
the proper type or amount alloys in them. Automakers marked their blocks to show
what different alloys were being used. This is holdover from those days and even
GM into the 1960s marked different alloy codes into different engine blocks for
identification of properties and uses. I do not know what the final "N" and
digit represent. Nitride has been suggested."
Serial Numbers
The engine serial number can be found on the waterpump boss at
the front of the engine:
From my research, the engine serial number should begin with
3J, and be followed by the serial number, so in my case, 3J39505.
|