Help with Valvesprings and valve float. Noob

yellow rose said

I'm getting lost here. If you just replace the bearings with bushings, you still have the same bearing area. Doesn't matter if it's bronze or aluminum. Think about the exhaust rocker. It has the same spring loads as the intake (talking W2-5 stuff here since I'm using my example) yet the exhausts show no more wear than the intakes with ~ 65% of the bearing area of the intake rocker.

My point is there is plenty of bearing area there. Push some bushings in where the bearings were and go. It will be fine.

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I disagree with there being enough area for a plain bearing if you only replace the roller element. Roller bearings have different load carrying capacity than a plain bearing for a given width. The plain bearing relies on a fluid film to be maintained and the area of that film determines the load. I'm not on top of the math behind it but from working with machinery I guarantee you that if you have a 1" wide roller or ball bearing, you will need at least a 2" or more wide plain bearing to replace it. Bearing surface velocity and other load factors affect it too. The bearing width on a stock 273 rocker is what, 1 1/4 - 1 1/2" wide and they still wear the shafts out over time with stock springs. Bottom line is I would not rely on a 1/4" wide plain bearing on either end of a rocker to live a long time in a high performance motor.