This 41 series 78 is my first Olds ever. To begin fixing it just got a shop manual and I am trying to become familiar with some of its features. The engine appears to be the original. It has the number visible on the left side of the water pump just as the manual indicates and as seen in the photo below,

Engine number LA433616


However, there are other large numbers on top of the engine block that I would like to know what they are. I show them in the following 2 pictures. From front to the rear of the engine head it reads GM D211 and then beginning just below the spark plug wires there is a longer number divided in 2 groups, initial group is 41641 and the second one is 412688. What are they?


GM D211 41641




412688

I presume GM is General Motors. The other numbers are part number for the head? Manuel

 

The D211 number is the date the part was cast. The other numbers are probably cast part numbers to identify the year of use.

 

OK. How can I decode D211? That will give the exact engine date then.

 

First digit is month . A= Jan , B=Feb , C= Mar , D=April , etc
Second and third digits are day , 21 .
Fourth digit is year , 1= 1941 .
So that head was cast on April 21st , 1941

 

Thank you ! That is very informative. Manuel