[madmaxx]

In the end it appears we will never know the open pressure of the springs. I am ignorant when it comes to cams, which is well ahead of most who think they know them, LOL. It appears to be a very aggressive street cam for a 408. Look at the new Ford racing 427 cam specs and it is not as aggressive and guaranteed to have hydraulic rollers. The force generatd by impacts are exponential as compared to constant loading, I assume the lash with solid rollers may allow the lifter to hammer the camshaft on the backside of the lobe, this usually doesn't happen with hydraulic rollers because the lifter would pump up and your valves would hang open and you would know you are doing it UNLESS you set your hydraulic lifters at zero lash, another slipperly slope.

In the end you will be much happier with a milder cam, hydraulic roller set up, reasonable spring pressure (300-400lbmax), then just drive and forget.