At one time, there were tools that could be inserted into a crankshaft oil passage to roll the upper main bearing shells in and out by turning the crankshaft. I've usually been able to do it by inserting a cotter pin into the oil gallery and flattening the ends down against the crankshaft surface. Turn the shaft, and the bearing rolls right out. It installs the same way.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!