Stainless, Bushed PRW Rocker Arms

It's easy to understand what the grooves do. They allow for a larger contact area of oil between the rockers and shafts. The old style stamped style paddle rockers don't need that because they have much less area of contact. The factory adjustable rockers or any other rocker that has full contact needs the grooves. What's not to understand? Just because "I tore one down that didn't have grooves" that doesn't mean it was right.
Exactly. Look at the small contact area just on the bottom and the area on the top where the oil can puddle. The non adjustables get over oiled it seems.

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