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400/4 main bearing shells

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Matt_Harrington:
Looking at my engine in many pieces, am I right in thinking that if I can find no distinguishing marks on the existing bearing shells, then I need to reassemble the crankcases and then use a bore gauge to find the diameter of the bore in which the shells fit? That measurement together with the journal diameter should then allow me to purchase the correct shells (?). Or is there a better way?

Oddjob:
Check the edges of the shells Matt, sometimes if you're lucky you'll find the old colour still on there. Ignore the stamping on the back of the shells, those are production marks, IF you can find any shell with a colour still on it then you can use the production marks with a reasonable degree of certainty. Any with the same exact markings will be the same colour, they have come out of the same box in the factory so should in theory be the same colour.

On the back of the crankcase, bottom section, are 5 letters stamped into the metal, these are the codes for the diameter of the journals, those are a good start. On the crank are markings that show what diameter the main and big end journals are, numbers for main and letter for big ends, same for the rods, a letter and a number, number is diameter of the journal and letter is the weight code, these will all be the same letter to balance the crank.

Try that.

McCabe-Thiele (Ted):
A starting point is the crankcase codes on the case itself the 5 letter on the rear -post them here for a starting point advice.

Ken has replied. Before me. I found the crank markings on the webs difficult to find but did eventually find them - they were almost like a dark shadow that did not photograph easily if at all.

Matt_Harrington:
Mmm, cases are off being cleaned and will report back when I have them in my grubby mits! Ken, I'll double check the shells again but I'm sure I couldn't see any colour markings. ....

Oddjob:
They tend to get washed off by the oil passing over them year after year. Worth a look though, some survive.

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