I wonder where he got that torque figure? I just looked at several charts for graded fasteners, and for bare (unplated and un lubricated) the torque for Grade 5 is about 475lbs/ft. For plated and lubricated bolts the torque is more like 350. For Grade 2 it's about half that, and for grade 8 about 40% more. Bolts all have rolled thread which are generally stronger than the machined threads as found on the crankshaft. So to come up with a suitable torque for a 7/8" machined thread in an unspecified steel would be a non S swag, IMO. Perhaps Phil was able to determine the type and hardness of the crankshaft and extrapolated from there?
The thickness of the nut may or may not have an impact on the torque figure. I was taught you need at least 1 diameter (of the male thread) of thread engagement to achieve full strength in a bolted joint, with 1.5 diameters preferred in order to provide a margin of safety. So if the 'thin' nut is roughly 7/8" tall then there is little to be gained by a deeper nut.
