What do numbers on cylinders mean?

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David Austin
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What do numbers on cylinders mean?

#1 Post by David Austin »

These are cylinders from my 1963 356B Super 90.
I was wondering what the numbers are telling me.
Three are the same :
I think the numbers in the circle are the date of manufacture that suggest to me 1976 10.2 which is either 10th Feb or 2nd October.
I'm wondering what "E" indicates and 7 in the triangle.
One is different :
It seems to suggest to me 1977.
But what does the "G" and 6 indicate.
Thanks for your help.
David
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Don Gale
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Re: What do numbers on cylinders mean?

#2 Post by Don Gale »

The markings A thru K are the cylinder bore diameter group numbers, E = 82.480-82.485mm. G = 82.490-82.495mm.

The numerical designation 5,6,7,8 inside the triangle are the cylinder height groups. I did not find actual dimensions for those, other than it's important that all 4 cylinders match the same height within an (unspecified) tolerance. Beyond that, I can only speculate that perhaps one cylinder height differs if the person assembling the engine noticed that the case deck height or the cylinder head bore depth differed from acceptable (unspecified) values.
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David Austin
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Location: United Kingdom

Re: What do numbers on cylinders mean?

#3 Post by David Austin »

Don,
This one has tested the community, much appreciate your answer which makes total sense. Thank you.
David

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