^^^^ Well how do stud mount roller rockers work? They have needle rollers that run on a fixed shaft [ trunnion ], just like needle rollers on a Mopar fixed shaft. Also, the same bottom loading occurs whether it is needle rollers or bushing.
I have ruined several sets of hard chromed rocker shafts by using needle bearing rocker arms even with a high volume oil pump and 70 PSI oil pressure. However I do use fairly strong valve springs with 500 lbs of open pressure.
I switched to bushed rocker arms and have had no trouble since.
Nevertheless, it is a very good question about how stud mounted roller rockers work and survive. I look forward to hearing the answer from others.
