It's my understanding that most engines were either run after assembly, or "motored" over by a big electric motor for a certain time without actually being fired up, to break in the parts and check for proper oil pressure, etc. A lot of commercially rebuilt engines get the same treatment. By the time the engine gets installed in the vehicle, it's been spun over enough for any disastrous assembly errors to show up.
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!