Man rod bolts on a car, truck or such tighten down from 45ft lbs. to 90ftl lbs. depending on vehichle. A SBC tightens at 75lbs. head bolts 90.
Props are tighten until you think your going to break something and then about a 1.4 turn lol. A backup nut will also help keep the nuts from coming lose. Had a wood prop that looked and felt tight but would scream at open throttle sounded like the motor was blowing up and rods coming loose. But ended up being just a turn or 1/2 turn from tight enough.