jacksoni- I wish I had the option of a box-end, but I need an open-end to get onto the locknuts when the followers are in place.
In the interest of continuing the "spinning" I assembled it (with the new locknuts) by setting the clearances, precisely noting the rotational position of each pivot stud, removing the followers, torqueing the locknuts with a six-point socket (a multi-step process, since the stud sometimes turns with the nut), then re-installing the followers. Very tedious and not an acceptable procedure for the future- I'll definitely need to develop an appropriate open-end wrench deal.
After some validation at about 6,000 RPM, spun it for awhile at 9,300, then 9,640- after which all seemed okay (turning the cam slowly with a wrench while monitoring the "feel" and sound of each cylinder's exhaust valve movement). But a short spin at 9,910 RPM resulted in a broken pivot stud. Not real surprising since there isn't much (or maybe none?) safety margin in my manufacture of these parts. I made them from grade-8 7/16-14 bolts, cutting the heads down to a 7/16" diameter hemispherical shape, then heat-treating to Rc-45. I admit to not attempting to calculate the shear stress that they would see- so I guess I'm lucky they "almost" sufficed. There
was some collateral damage this time- the follower's ball-seat got beat up a little, so one of the "spare" CNC'd followers will get pressed into service. Once again the testing will be interrupted while I get the follower body shot-peened and heat-treated, and assemble wheels and axles into it. Plus investigating shear strength improvement of the studs- better material, smaller oil hole, etc.
P.S.- Hindsight truly is 20/20- I shouldn't have ignored the fact that the torque seemed to level-off at about 65 ft.lb. on the locknut of that one stud!