[Steve C.]

"I can't remember the springs Dave set up my heads with, but they are the same ones he uses for HR camshafts. I'll ask him about the pressures again, I was thinking he said they were up near 380-400 lbs open."

I have a copy of the specification/flow sheet for a set of aluminium d-port cylinder heads set up from SD Performance for a hyd roller cam, it says this:

".... ported and set up for hyd. Roller, Crane 99893 springs set up at 1.780"-1.790" intake & 1.810"-1.815" exhaust installed height, titanium retainers."

These heads were bought with the intention of running solid roller lifters on a hydraulic roller lobe. After the engines dyno session a set of springs were removed and measured. Keeping in mind that valvesprings can 'settle in' and lose some pressure after run-in. The actual installed height was 1.785" and it had 145 lbs. seat pressure. Rate for that spring is 391 and the net lift was about 0.602". Running apparantly with no issues, but based on my consulting of various professional cam designers and tech people around the country on the subject this in my opinion is margional for the application with the valvetrain mass involved. When in doubt, run slightly more seat pressure... NOT LESS. The extra amount of pressure may save you from issues and that extra amount of pressure WILL NOT shorten the life of the springs enough to worry about, nor will it cost enough power to even bother with.