there are different application for things as well , RAce parts have a limited lifespan & are regularly replaced but tend to be lighter , street parts need to be heavier & more durable , same with con rods , many race engines use Alum rods & they have an approx lifespan of 50 passes & then they are replaced but would you use a alum rod in a 100,000 mile engine ?? common sense tells us that the rockers do not touch the shaft , if it did it would weld or score immediatly ,so more surface area has to reduce load on the shaft , I have seen needle rockers wear grooves into hardened shafts before as the surface area is small 7 the rocker doesn`t move very far so I prefer & bushed or machined rocker with closer to 1" sq surface area over the .001s of an inch of surface area needle brgs offer , just my preference for street engines
