I had my rockers off the other day and noticed a few of my valve ends aren't wearing evenly with the others. My understanding is the tappet is slightly offset of the center of the valve which causes the valve to rotate when it applies the down stroke force. So I have three valves that have rotated less than half way in ~100miles. How bad should I worry about this? Is there anything short of Machinist voodoo that would solve it?

EDIT: Sorry. On a R series engine if that wasn't obvious.

 

Watch the oil you use. Most oils don't have enough ZPPD to produce sacrificial layer to limit wear. ZPPD was removed or lowered from most oils to prolong catalytic converter life. But is bad for our engines. Yes this is true for many big name spendy oils too.

 

Man not only did you make me read Bob the oil guys, but now I'm wondering if it's smooth or rough wear I saw because I neglected to feel it or forgotten. I think your subtext there was I probably shouldn't have noticed any wearing given the mileage, and yes the wear should be even due to the valves "natural" rotation.?

SF is the pre 88 oil rating
​​​​​​ f1 at .10% f2 at .12%. API grades are 0.10% max.