I imagine the number would be in the millions.......
That is the number of engines of various makes that used ductile iron rockers without being bronze bushed on steel shafts........& provided millions of miles of trouble free service. My Poly engines were among them.....
Post #10 would be the safest way to bush rockers...
You are 100% correct and I agree. However, my friend down under, those millions of engines didn't have squat for spring pressure either. Just something to think about.