Are you sure it's a hydraulic cam? If its a solid roller cam and you put a hydraulic lifter on it it will to exactly what you are talking about. Zero lash= purr like a kitten even just a couple thousandths preload and no idle...

I adjusted mine with each cylinder at TDC on firing stroke - did intake and exhaust together. Ran through the firing order this way. I figured they both have to be closed all the way at this point. SB and MT's method makes my little pea brain hurt too much! :D