Valve spring calculations

[The Struggle]

Hey Guys,

Just recently posted my engine build on a different thread (Under The Struggle - first engine build) and while i was reviewing and researching my products list for my new 388 c.i. build i noticed that my cam vs. valve spring max lift was a tad bit close. Actually it's(Cam @ .534 max lift for intake and exhaust.) Max lift as stated by edelbrock for there #60899 RPM head springs are .575 which is what i rated as much lift for my cam with a little bit of a threash hold for valve spring to not bind up. So my Cam is originally spec'd @ (.501 lift intake and exhuast, but 0.534 when i add my 1.6 roller rockers FYI) i believed that this set up would be within range and safety, but i researched on and found the specs for the Valve spring to be...

Valve spring# 5825(N)-non rotator type

SEAT Pressure: 128 lbs.
Installed height: 1.800"
Open Pressure: 338 lbs.
Outer Diameter: 1.460"
Inner Diameter: 1.038"
Coil bind @: 1.150"
Retainers: #9611

SPINGS ARE FOR A HYDRAULIC FLAT TAPPET CAM WHICH IS WHAT
I"M USING....

So just making sure i was in spec with the cam and springs i applied this formula gained from ( http://www.yellowbullet.com/forum/showthread.php?t=414628 ).....

coil bind + your clearance + NET lift = installed height

My calculations are: (Below)

Coil bind: 1.150"
Clearance: .060" (for maximum safety value for coil bindage)
Net Lift: 0.534 (with 1.6 RR)
Installed Height: 1.800"
----------------------------------
1.150+.060+0.534 = 1.744

1.744-1.800= 0.056 clearance not to include the 0.060 i gave it under the formula.

I know under the formula that the sping should capable for the cam, but i revert back to the Max Lift for the spring to be no more than 0.575 for bindage, but am i under my formula to close and over pressing the spring to cause damage over time? I added double clearance, but i would like you guys to check the numbers with your knowledge to see if i missed anything.

Thanks for the help. I'm slowly learning every day!

-Blaine

 

[bucket]

I'm no expert, but here's my thoughts:

Installed height only has to jive with the heads the springs are installed on. The heads you are using have the correct springs installed already. So as long as your cam doesn't put the springs into coil bind, they just need to be fairly close to the recommended spring pressures for the cam. Also, is that .575 max lift because of coil bind or because of valve guide clearance? From what I remember, it's valve guide clearance, but it's been well over a decade since I installed my Eddy heads.

 

[The Struggle]

Eddy didn't say on their website so I went with it recommending for coil bind seeing that the cam they used for the original set up was in the mid .400 lift range. But I haven't seen a manufacturer that states anything on whatvyouvsaid but I could be wrong. I'll keep digging and see or give them a call.

 

[bucket]

Your cam's lift won't be too much for the springs/heads.

 

[The Struggle]

Ok I'm sure it will be fine too. Thanks for the help!