Hello, I'm currently checking the main bearing sizes for the K6 engine which I'm restoring. The main bearing crankshaft pin second from the alternator measures 35.985 in the mic. and the crankcase sizes are all B. With plastigage, the clearance on this bearing measures approx 2 x .045mm using a black bearing shell, i.e. the plastigage is only flattened to half the width of the .045 measurement i.e. about .09mm.
The mainshaft pin third from the alternator measures 35.980 in the mic. but .045 clearance with the plastigage. Given that this pin is smaller, why does the plastigage read half the clearance when the main bearing crankcase opening is the same size and the pin is smaller? Is this due to the B crankcase measurement having a tolerance? I've checked the mic. against its standard 25mm test piece and it seems o.k. Also, The Haynes manual says that the limit on the crankshaft is 35.94mm but bearings aren't available for this size. Are thicker bearings shells available? I've checked with black, which are the thickest but the clearance seems excessive. The crank looks in good condition with no bluing or pitting. I'm tightening the crankcase bolts to the torque spec.
Any help most appreciated,
Cheers, MikeJ