Seat Pressure and Open Pressure

[nivvy]

Since I am learning to build my own motor now I have a question as to seat/open pressure

Seat pressure can be adjusted and open pressure cant.... open pressure ='s ---- seat pressure + (cam lift*spring rate) so a seat pressure of 200lbs + (.627lift * 713 lbs/in) ='s 647lbs of open pressure ..... right

Also are these good numbers....it is a solid roller cam & k motion k1000 springs...

[gkring]

open pressure goes up with seat pressure, which I think you understand by your formula. Shimming the installed height will raise seat pressure and also raise open pressure. Numbers sound fine. keep them as low as possible for longer valvetrain life. Valvetrain weight and RPM you plan to spin it have alot to do with it as well.

[cudabob496]

I have a .625 solid roller, and I think the open pressure on my valve springs is about 470. Your 647 seems to high, but I ain't no expert in this area.

[Chryco Psycho]

Check for adequate clearance between the coils if you shim the springs ....coil bind is bad

[nivvy]

I dont think 647 is too high you 470 seems low... according to my book....considering jesels are 300 on the seat and up to 1000lbs open.... like I said I am new to building my first engine ... my kmotion k1000 are some exspensive springs...200lbs seat pressure... CP spring height is 1.970 & coil bind is 1.090.....shimming the spring will raise the seat pressure also right.... my engine building book says to start with 200lbs seat pressure at a minimum for a solid roller cam....   thoughts

[Chryco Psycho]

the cam should have specs for exactly what pressure it needs , Have the spring tested to be sure the pressure is adequate at the height you have