I think it is a stuck valve. I ran it till it got hot and started making the whack sound again - all new lifter, rockers and springs on passenger side. Can see and feel the first rocker slapping around. All the others look smooth and when placing a small screwdriver on the tip of the rocker they all feel smooth expcept for the first one on the passenger side towards the front. Swapped out the rocker and lifter real quick and same thing again. Was about to change it again and as I was compressing the spring down I noticed that the valve did not slide down easily with the spring like all the others - the valve keepers almost came off - I had to push the valve stem down with a screwdriver as the spring was being compressed to put the rocker on. So- I'm assuming that is a stuck valve - now what - how do I unstick a valve without pulling the head and doing a valve job. Or is that the only way to unstick it? Thanks