What are you trying to do and what spring are you trying to do it with?

 

I've run them @ 350lbs with no failures, no need to go any higher.

PowerStrokeNation - View Single Post - Comp 910 springs

 

Seat spring pressure?????????? I think you meant at lift according to you write up.

JonFord

 

Oh I agree, but the man ask for valve seat pressure.

JonFord

 

150lbs of seat pressure is about the max you should need, right?

 

That depends on how much boost/drive pressure you plan to run, what RPM you plan to run it up to and how much lift.

I'm runing something like 180ish lbs because that's what Comp Cam's told me to run when I gave them the specs for what I was doing. Haven't had a rocker, or lifter, problem yet.

Rather than try to figure it all out yourself I'd just give a cam manufacturer like Crane or Comp a call and tell them what you've got and what you're looking to do and they can tell you what you need.

 

That is why I asked the question. I was working with crower and they came up with a set with 160lb's seat pressure. The stock is like 90 or so, Thats why I asked the question.
Don't want broken rocker arms.

 

You should be just fine with the 160lbs of seat pressure. Did they recomend an over the nose pressure as well? These two figures with lift will give you the spring rate you need. Then with the installed height you can find a spring that closest fits your needs.

 

There was nothing asked or said about the over the nose pressure. I was just told that with the info I gave them the spring that are on the way will work.
Will see when I install them and run it.

 

I's ask machinist or hod rod seems a good q for them.
also tarm had some good info a while back on seat pressure.
but use and needs have a lot to do with it..
ie high hp mods with exhuast braking etc..

 

Just remember that boost and drive pressure are PSI.... multiply that times the area of the valve face and that is the direct pressure that is trying to hold the valves open. That pressure needs to be added to your calculations from your cam manufacturer for seat pressrue.....

 

That said matt what seat pressure do you want me to get on my 910's with your stg 1 and roughly 40psi of manifold pressure?

 

125 is fine at that level.

 

Thanks for the straight answers. This information is really helpful.

 

Are you running new stock cam? Or is this just replacement springs for current motor? Curious about replacement springs myself. Mike.