An old dirt track racer I knew used to rebuild stockish engines for local folks. He would set the oil pan and trans on some old tires and fire them up to break them in right there in the floor.
Same way the junk yards did back in the day.
Would have manifolds and the short pieces of heads pipes cut off with a fire wrench.
Even if smoked and rattled some on start up thet would say something like, purrs like a kitten. If ya have a problem just come back in 30 day's.
One place was known to sell almost anything that fired up.and ran that did not knock.
