You need to be sure the valves are completely closed before making the preload adjustment. It will take several minutes for the lifter to bleed down to a fully-adjusted position. I like to use what's called the "companion cylinder" adjustment method, where the cylinder that's between exhaust and intake provides the position reference for the one that's halfway around the firing order, on TDC compression. I've explained it several times, so an archive search for "companion cylinder" should locate one of the threads. I consider it to be the most accurate way to adjust all valves, solid lifter or hydraulic.
Jerry

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