Just a guess; I think by checking for zero lash by turning the pushrods, you got them too tight rather than zero lash. You should have been moving the rocker back & forth while tightening to zero lash. I think by going until the rod wouldn't spin, you were way too tight already.
Quickest (but messy) way now, is to remove one cover at a time. Then at a low idle, back off each one til it Clacks loudly, then gradually tighten til the loud clack goes away, then do the one turn. If you do the one turn too fast, you will feel it miss a little as the hyd lifter "adjusts" itself.
Oil will fly all over if you don't have the little clip-on deals that are made for adjusting valves; maybe throw a clean rag over them to stop the spray.