Some roller lobes need more pressure than other, always get the recommended springs as the per the cam manufacturers recommendation. 557" RB Indy engine, comp custom solid roller with 285ish at 50. and .800+ lift with Jesel 1.7 rockers. I ran titanium retainers, PSI springs with about 300 seat, and 760 lbs open pressure. Spin it all day long to 7500+ rpm. has seen as high as 8K by accident

[color:"red"]65 Hemi Belvedere coming soon [/color]
[color:"#00FF00"]557" Indy engine 1.07 60ft 144mph in the 8th 2100 lbs package [/color]