My Engine serial number is 302514
According to the oldengine dating pages, my SOM was build near the end of 1938!!! Just before the war started, OMG!!! Its the same age as my father!!!!
This is scary now
That is because you didn't use the correct dating information!
302 is the serial number
51 is a 5/1
4 is the year of manufacture added to 1950 = 1954
There are 3 main dating processes, all them work well if you understand how the apply to your particular engine number.
ie:
CS43354 = Old system
303514 = second system - NOTE: number of digits usually gives this one away.
The later still method applies to very late air-cooled stuff and is probably not appropriate to this forum.
Listerdiesel