When a rod is reconditioned, it's filed slightly out of round, or in the case of your insert-bearing conversion, it's bored out to accept inserts. Torquing the rod nuts sets up some stresses, and then the rod is honed perfectly round, and the correct size. Pressing new bolts in will sometimes create stress points that pull the big end out of round, so when I was working as a machinist, I'd always file the mating area of the rod and cap a little before installing new bolts, then hone them round again. I'd only reduce the size a couple of thousandths, but it made for an excellent end result after honing the rod for a final fit.
Jerry
