It is the lifter design that determines preload so you must know how much preload the lifter requires.
Comp has one lifter that is designed to run at basically zero preload-.003", I believe.
The other runs at a more conventional preload...some thing like .020"-,040".
Knowing which lifter you have is the starting point.
In the second case, it should not be sensitive to the the setting, particularly at your current preloads.
With adjustable rockers, it is easy if you know the thread count of the ajuster. For instance, 20 tpi means that one complete turn is .050".
So you know that a half turn to three quarter turn after zero preload is a good range.
If they are 25 tpi, then one complete turn is .040"
Roller cams are like conventional flat tappets in that the lobe ramp design makes some cams a bit more tickety than others.
I believe that I just said I doubt it will make any difference if you have the second type of lifter.
