Mgb big end shells

[bluetr3]

I wonder if someone could kindly help me to identify the undersize my engine’s big end shells.
The stamping on them is as follows:

County C4403 060 MM

If 0.60 mm in inches = 0.0236, this seems a strange undersize, and I am not sure that they are correct. These were obtained from Moss, and fitted be me about 14 years ago, the mains are Glazier at 0.030 u/s (no problem with those) I am rebuilding the engine due to piston ring failure, and I need to also replace the big end shells with correct undersize. The crank is in good shape with no bottom end problems for the last 70,000 miles. Any help would be most grateful.
John

[Ian F]

As far as I understand, "AM" signifies bimetal bearings and "CP" indicates trimetal (superior). So MM not necessarily meaning millimetres.
Probably 60 thou undersize?

If you have the engine dismantled I would advise getting the crank journals checked for size and ovality and getting things just right before putting it all back together.

You could try asking your local engine building company, or post something on the US site - MG experience, if you don't get a definitive answer on this forum.

Ian F

[Ian F]

https://www.mgexp.com/forum/mgb-and-gt-forum.

[bluetr3]

Thanks Ian
I am taking the crank to be checked out. Incidentally This time around I am using Nural pistons, OE standard. Definitely not County. Saved £120, from Engineparts(UK), also supply ACL trimetal bearings, Vince, very helpful guy.
Thanks John