Datsun Roadster Forum-311s.org

I had a discussion with someone a while back (and I don't remember who it was unfortunately) that one issue that several of the cam grinders have is that they grind the U cams with the same lobe profile as the L-series cams. The rocker geometry is different between the two engines and the U requires a different lobe shape than the L-series. As I remember the conversation it is most evident in the closing and the rocker briefly losses contact with the lobe and then smacks back on to it, leading to abnormal wear on the lobe and the rocker.