I was tested by this set of flywheels. Normally I can true a set of wheels over a period of a few hours at the most. This set just wouldn't come into true. After too long fighting with it I decided to take the wheels apart and here is what I found. A significant portion of the crank pin threads had cracked off and fell apart when I took the nuts off. They were torqued to spec, 150 ft lb.
This was a NOS complete rod set from old Dixie Distributing stock; rods, crank pin, nuts, rollers and cages. My assumption is that there was an error made at heat treat and they were made too hard and not tempered properly.
I purchased a new USA made Jim's crank pin and Jim's crank pin nuts. I had to lap the rod races since the Jim's crank pin was ground .001 larger than the Dixie pin. The wheels were much easier to true this time. I am thinking that the Dixie pin may have not had the taper ground exactly right either, making it impossible to true correctly.
I was happy as hell to move beyond the flywheels finally!