Bore is 3.628"-3.629" X 4" stroke and crank is mains 2.125" and conn. rods are 1.999" and valves are set .008" hot so add about .002" more for cold setting. I don,t have a parts book on the undersize bearings and can,t remember what is available but .020" under sounds about right. There may even be .030" under available but not sure without a book. If you need any other spec. I have a factory sheet here on it and other older Cat engines starting and diesel.