Not talking about pressure. Talking about the travel of the spring. There should be at least .060 more travel in the spring than the full lift of the valve to the point where the spring goes solid. Preferably closer to .100 more travel. Sounds like you possibly could have floated the valves too. Actually the spring should have had enough travel in them but if you floated them that is a different story. How many RPM's were you trying to spin??? Or did you have shims installed under the springs to increase the pressure?? Shims are to be used to adjust installed height not to increase spring pressures.
BTW this was caused by coil bind.