Jerry,
I'm curious about the engine failure you're talking about. As a hypothetical, let's take my engine. If I torque the bearing caps down, my crank locks, which suggests I'm well under .0015 spec clearance, with the original non-undersized bearings. If I shim the bearing caps, I have control over the bearing to crank clearance, at least up and down. So if I get the clearance to spec (.0015) what's the failure mechanism? Is there a risk that the side to side clearance is so out of whack that oil loss though the horizontal sides of the bearing starves the bearing? But anytime you shim, you're affecting the up and down clearance, so I would think this could always be a problem? Does the torqueing down of the bearing caps snug the bearing all the way around the crank so clearance is uniform?
I do deal with some high HP high speed rotating equipment in my work life. So now curious if idle speed is enough to initiate hydrodynamic lubrication, or whether the bearing is operating in a mixed or boundary condition at idle? And to take this further, how does the reciprocating motion on the rod bearings affect the hydrodynamic condition when it forms?
Looks like I turned up some research to do. I'll still purchase the correctly sized bearings in the end, but looking to understand how these bearings operate better. The constant load/constant rpm stuff I work on is a little bit of a different animal.
Thanks,
Mark
