What is the recommended valve spring pressure for a blower application (5 PSI Boost)? I was running 120# springs. Before I put this engine back together, I'd like to see what is the correct pressure to be running and change them if necessary.

Thank You,

kirk

The cam profile is what determines necessary valve spring pressure. Consult with your cam manufacturer for recommendations.

Call your cam manufacturer and they will recomend the type of springs and thier pressures.

A friend of mine runs springs that are 400#'s on the seat and over 1000#'s open in a small block chevy. Well a 970hp SBC. I heard those numbers and was amazed ! I run stuff that is around 200/570.

Agreed.................This is the best way to go, it's not the boost, but the cam profile that dictates what springs you'd use.

Most importantly need to know what type of cam: flat-tappet or roller, hydrailic or solid.

Boost makes the same pressure on the back of the intake valve as it does everywhere else=your making 5psi so 5# per inch over the face of the valve, say 2.19" diameter. That's about 1.72 sq in at 5 psi is about 8#. So the pressure you need to offset the boost is less than 10#. If you set up your springs according to the manufacturer's specs, you don't need to worry about almost any boost we usually run on a boat.