By "rocking" I mean exhaust valve closing and inlet valve opening, so the other cylinder is on the start of its power stroke. Cylinder 1 rocking - cylinder 4 at TDC, start of power stroke.
I hope that makes sense.
Or get the valves on no1 cylinder "rocking" and adjust both valves on cylinder 4. Likewise. get valves on cylinder 2 "rocking" and adjust cylinder 3.
Even easier and less engine turning and is just as accurate.