Well, tore the top end off the engine the other night. It is a lot better than I was expecting. It comes down to a "stupid human trick". A while back I pulled the rockers and checked a suspect spring problem on another cylinder. While reassembling the valve train I accidently tightened down the rockers with the pushrod out of the lifter cup on #4 exhaust valve lifter. After finding it and replacing a bent pushrod, I reassembled it correctly. Unbeknownst to me, I damaged the top of the lifter. It swelled the lifter at the top edge. My losing of lash was caused by the lifter just barely sticking in the bore. Weird thing is, I had checked the valves 2 times since than and never seen any issues with lash. When I pulled the head and found nothing wrong with the valve or seat, I went to the lifters. It was stuck, but not too tight that I couldn't pull it out with 2 fingers. I could also push it in to the base of the cam by hand. So, all in all not too bad. Chalk this one in to the lessons learned column. Thankfully the roller and camshaft have no damage.
Beep