Thread: What exactly are grade B pistons?

I have what I suspect to be a gudgeon knock. I think it's the pin to conrod joint as I've got low oil pressure also; but it's an opportunity to put hc 4.0 pistons in.

When doing the head gaskets not long ago it seems there are grade b pistons already in the motor. These seem to be 15 thou bigger than grade A.

So does this mean the sleeve had been bored out 15thou for these pistons?

I suppose the trouble is that no retailer seems to stock grade B 4.0 pistons...

There's no oil pressure to the gudgeon pin, it's splash lube in the piston only. I've never actually seen worn gudgeons on a LRV8 in any case. I'd be pulling down the motor and looking for cam wear, cracked pistons, loose liners etc before measuring the bores accurately and ordering to suit.

I doubt seriously if graded pistons are more than 1.5 thou oversize, no way the factory would fit 15 thou oversize.