Valve spring close to coil bind: good or bad for spring life?

[ptuomov]

One thing I read:

“This is why it is important to use a beehive or conical valve spring within 25 thousandths of its coil bind height when the valve train goes over the nose.”

http://www.cpgnation.com/valve-spring-t ... -revealed/

[amcenthusiast]

I was just plugging in the hard-to-find information I'd found by searching many other alternative sources.

It seems to me... that if the springs, very near to coil bind are 'surging' and the individual coils make contact, this would send a whole new set of 'ringing vibrations' into the spring (and all other associated parts) to plausibly increase chances of harmonic resonance and failure.

Seems like I've always been taught not to nick a spring either, as this may damage the hardened 'skin' of the spring steel.

More speculation, it seems like if the springs rub, maybe in a near coil blind spring surge situation, this will gradually wear off some of the surface hardness of the spring steel?

Would a paint on a spring act like an 'EP' lubricant during times of spring surge contact?

Here's another good article written about valvesprings & camlobes by EPI, Inc.:

http://www.epi-eng.com/piston_engine_te ... basics.htm

[modok]

It might seem like a bad thing...., but many millions of valve springs in the 70's especially had "dampeners", which rub ALL the time, and yet that worked well enough.
Interference fit dampeners DO wear the spring, but rarely see more than say .010 wear from normal service, as they are very hard material.

Progressively wound springs, which have been used even longer are also food for thought.

The more tightly wound coils at the base of the progressively wound spring of course do touch fully every cycle, but it isn't BANGing you are thinking of, they ROLL together, and the wear from that is very minimal.
This seems to be important principle, to space the coils differently so they do not hit at the same time, but progressively roll together.
I noticed when I first saw an Chevy LS spring, the center coils were very wide spaced, and the bottom coils closely spaced, took a long time for me to understand the reasons why they did that, but, now that I get it, IMO it's a great idea.

If you look at many broken valve springs (normal ones with even spacing), you'll see they tend to break more near the end, and that's also evidence for spacing the coils wider in the middle and tighter near the ends(or beehive) even without understanding why. Just going by the signs. Have you wached David V's vid on springs?

[modok]

[ptuomov]

“This is why it is important to use a beehive or conical valve spring within 25 thousandths of its coil bind height when the valve train goes over the nose.”http://www.cpgnation.com/valve-spring-t ... -revealed/

For what it’s worth, I don’t believe in this advice, at least not with DOHC direct acting bucket or light rocket arm setups. If you look at the 4V cobra mod ford 4.6L beehive springs from PAC (PAC-1223), the recommended installed height at valve open is 0.070” from the nominal coil bind spec and a full 0.100” from the actual measured coil bind. (0.970”, 0.900”, and 0.870”). Furthermore, over the last ten years the recommended installed height at valve open has gotten further away from the coil bind.