273 rockers on e-heads

I keep staring at it but nothing changes.

I checked that the shaft is straight and the tips of the valves are level. No problem.

I taped up a pair of channel locks and tried working the spring around a little bit but nothing seemed to change. Then I grabbed the top of the spring and gave it a little turn CW and now I've got clearance. I'm not sure what that tells me, if anything.