what should my oil clearances be? are important are they? should i be **** and afraid the engine is going to fail if they aren't perfect, or do they give a good bit? any measurements i should REALLY be meticulous on?

 

they should be what your manual says, go buy a manual. yes they should fall within spec, if not grind the crank or mix and match bearing shells with +.001 or -.001 shells, as long as you're standard. you should pay close attention to anythnig with a spec, measurement or torque.