If you are using nonjv head and valves, which normally came from a non hla engine, your valve stems may be too long to close with hla rockers. I had this happen once. You either need to use the manual adjust rockers or change the valves. I had this happen once. To test it, see if a rocker on the cam base circle (fully open) will rock with hand pressure a few thousandths. You can feel a slight give in the rocker. If the rocker is dead solid, you gotta change stuff out...

Not responsible for advice not taken...