You need to add about .060" to the available compression to allow for some clearance to coil bind at max valve lift.
Spring rate is easy to figure:
- Take the listed seated pressure and installed height and compare to the open pressure and that corresponding height
- Subtract the seated pressure from open pressure
- Subtract the open height from the seated height
- Divide the difference in spring pressure by the difference in height
- The result is spring rate in lb's/in
- This applies for any 'straight rate' spring, i.e., a standard coil spring, including singles and duals, with or without dampers. (This does not apply to behives, which are progressive rate springs.)
