[Tommy]

I'm far from an expert in this topic, so take what I say with a large grain of salt. But I had to learn about this to deal with a problem last year. What I think I know is this. If everything (e.g., lifters, push rods, valve stems, head thickness, etc.) is exactly the right dimension, the lifters will achieve the desired preload exactly when the nut that holds the rocker on the stud reaches the torque required to hold the nut in place. If that combination of events does not occur simultaneously, one method of adjusting the geometry is to get a different length pushrod. But the new pushrod has to be exactly the right length. .. However, I heard of another solution that seems far more certain to me. Someone sells an aftermarket stud with a lockable nut. This allows the nut to be tightened until the lifter preload is correct, and then the nut is locked in place to secure the rocker. I don't recall the name of this aftermarket product.