A friend of mine just had a crankshaft replaced on his 346cid with a new crank and bearings. He retained the original pistons and rods, the only thing that was changed was the crankshaft. Would he still have to perform a break in procedure? or can he just start romping on it?

 

1) There is nothing to break in with bearings. No reason why your friend can't get the engine to operation temperature while monitoring the oil pressure, then give it hell if everything looks good.

2) Not that it applies here, but with new rings, the sooner you can romp on it the better. Breaking in rings is all about applying enough cylinder pressure to make them work as they were intended. More info at http://www.mototuneusa.com/break_in_secrets.htm