Valve Spring Life

[FoMoCo]

Question about Valve Spring Life? How long do they last in a boat? I have been running the same springs for 4 years with a Solid Roller. The boat was spinning 5300(429 BBF) with the first motor for the first 2 years, then I built a bigger motor (460BBF) with a bigger solid Roller, which I am running right now, and the boat was spinning 5700rpms. Here is whatÂ’s going on. I put new bearings in the motor and put it back together for spring, I also installed new Valves in the heads along with a 5-angle valve Job. The boat ran the best it ever had, pulling close to 6000 rpms (Oh Ya I had the heads ported to). That only lasted for 2 trips to the lake. Its been slowly losing Rpms. It now only spins 5600rpms. I thought it was a Valve adjustment issue, nope I checked them like 3 times. I did a compression test, no issues, itÂ’s actually better then it was last year! (I think the good valve job helped) So I am starting to suspect The Springs are finally giving out! Somebody please give me your 2 cents!! Oh Ya the Cam is a Comp Cam 300AR with .663 lift and 254 dur @ .050, 110 lobe sep. The springs are also Comp Cams PRT# 938. 210lbs closed and 540lbs open pressure.

[Fiat48]

Valve spring life is dependant on the spring material and the camshaft profile. Best way to do would be to check the seat pressure with a Moroso (or other) tester or remove the spring and have a machine shop check the pressure.

[cstraub]

Agree with Fiat. . .if it is a solid and under 160#, springs need to be changed. Good thing to do is when springs are installed, use a on the head checker and reference the pressure, periodicly check them for pressure. Anymore then a 20% loss, you need to change them..seat pressure is the critical measurement.
Chris

[Fired Up]

Will weak spring pressure cause you to lose rpm's or just break parts? I thought weak springs would allow floating and banging around of the valve train ultimately causing damage.

[Fiat48]

Originally posted by Fired Up
Will weak spring pressure cause you to lose rpm's or just break parts? I thought weak springs would allow floating and banging around of the valve train ultimately causing damage.
All of the above. Just depends on cam profile, clearances and how weak the springs are.

[sgdiv7]

Nope, that hapends when they get real week. sounds like they are just bouncing now messin up the air flow. I think they are 20 lbs or more under the min. spring psi.

[cstraub]

Bouncing will bleed cylinder pressure, then you loose dynamic compression, and the result is loss of rpm. Hammer the seats long enough and valves will break and seats will need to be replaced.
Chris