Whatever pre-load you use (1/2 turn, 3/4 turn, etc) isn't really that critical. It's just to make sure that you have eliminated any lash.
Just be aware that this can only be done one time.
In other words, you can't set your pre-load and then go back around the rockers to "check your work".
If you have any doubts that you pre-loaded correctly, and want to do it again, you'll have to start fresh.
Back the rocker nuts off at least one full turn from where you were. Then walk away and wait an hour or so. That will allow the plunger spring to drive the plunger back up to the top of it's stroke.
Zero lash can only be determined when the plunger is at the very top. When it is at the top there should be no gap between the cup/socket and the circlip.
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