The main bearing clearances appear to be incorrect on the "Factory engine specifications" on this site. They are listed as .0003-.0018. I believe that should be .003-.0018 or 1.8 to 3 thousands. My Haynes manual says .0003-.0018 also. I believe that is a typo. Any takers?
Dale, I agree. It has to be a typo. .0003" is too small to allow the proper flow of oil. Another factor is cranks usually have a runout of .0005"-.001" This means that when supported by vee blocks on the front and rear mains, even the best cranks center main will have a tiny wobble. That means it's not running on the same centerline as the front and rear mains. It follows that with .0003" clearance, the center main is rubbing by at least .0002". It's really a complex subject having to do with the viscosity of the oil and the pressure and flow of the pump. I believe when you get above .003" the parts start to generate noise. Noise is energy and you are not putting that energy into the crankshaft. Excessive clearances also allow pounding which crushes the oil film and parts will start contacting each other. If you use a general .002"-.003" clearance, you will stay out of trouble.