One of the real fast Mopar old time racers told me to make sure when setting the lash to make the feeler gauge was real tight to push in after setting the valves, real tight. I set the lash and add around 1/10 to maybe 1/15 additional turn before tightening the locknut, tighten and check the lash, adjust as needed on the tightening and adjusting When the feeler gauge drags out hard I know I'm close