Or you can warm up the engine---then remove a valve cover--start the engine--one rocker at a time loosen the lock until it clatters, tighten til clatter just goes away, go to next rocker in turn, switch to other side and do the same

Caution--can be messy, oil will smoke from the exhaust manifolds,however you will set the running valve train for your oil and pressure---

Also if you have any flat cam lobes you will notice that the rockers don't move as much as others
If the pushrods aren't rotating you have a flat cam/lifter issue