Hyd Roller vs Hyd Flat tappet on SM heads

Spring pressure for hyd roller can vary, but usually fall into the 135 seat and 360 open range. Solids..depending on ramp speed and app can be 120 to 160 seat
depends on the cam. Always follow cam manufacture recommendations for spring pressure.

Thanks MO, but just to be clear, these are both slated as hydraulic lifter heads (springs). I also noticed the spring height is different on these as well. 1.8 (hyd roller) vs 1.9 (hyd flat tap).