looking far info one how much spring pressure you can run on manley stainless steel valves like the street-flo & race-flo valves 11/32 stems how do they rate them rpm or spring pressure sure dont want to brake one i,m looking at 200 seat and 530 open at 600 lift solid roller
You should be ok with that. I run 590 on mine, no problems in 2 years (yet). If you want peace of mind, you could go with Titanium valves ($$$$$). The main concern is that they're one-piece. 2 piece valves WILL break, its just when and how much damage will be done.