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· Registered
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Discussion Starter · #1 ·
I know my seat presure and lift preasures are good but is there a geometry/resonance reason why the installed spring height has to be a certain distance?

If I have enough clearance between the coils/ retainer & valve seal at max lift can I call it good and go on?

Thanks
 

· Some guy
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3,641 Posts
I know my seat presure and lift preasures are good but is there a geometry/resonance reason why the installed spring height has to be a certain distance?

If I have enough clearance between the coils/ retainer & valve seal at max lift can I call it good and go on?

Thanks
It sounds like you have it correct. Installed height is determined by what spring pressure you want to run on the seat, and the spring rate dictates what the open pressure is, so if both fall where you want them pressure wise, and you don't have coil bind or interference between retainer and seal, and your rocker arms clear fine, sounds like you are good to go.
 

· steelcomp was here
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11,830 Posts
Installed height is a couple of things...seat pressure and open pressure are one thing, but it's also important to have the spring as close to coil bind (meaning within allowable limits) as you can at your max lift. If it means a few extra pounds, I aim for the open dimension of the spring over the exact pressure. If you've chosen your spring correctly, you should have all three. If you still have .100" of spring travel at your max lift, you may have the wrong spring.
JMO
 

· northern member
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611 Posts
on a flat tappet , i'd sooner have the little extra installed height if you have enough pressure on the seat and not have any more open pressure than what you need for the r's you turn . if your boat isn't seeing the big rev's the extra presure over the nose is just goin to wear things out that much quicker. but mostly roller now with insane lift and min. coil clearance , Steel you like something closer to .050 , suspose to cancel the vibration's out ? sure does squeeze the $hit out of them:))eek:))
 

· Premium Member
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26,163 Posts
on a flat tappet , i'd sooner have the little extra installed height if you have enough pressure on the seat and not have any more open pressure than what you need for the r's you turn . if your boat isn't seeing the big rev's the extra presure over the nose is just goin to wear things out that much quicker. but mostly roller now with insane lift and min. coil clearance , Steel you like something closer to .050 , suspose to cancel the vibration's out ? sure does squeeze the $hit out of them:))eek:))
It would seem that way, but all the cam companies a swearing by it. The springs are designed for "solid state". You can't over stress them before they go into coil bind coil bind.



 

· Sit N' Spin
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1,345 Posts
Installed height is determined by the depth of the spring seat in the heads and valve stem length.

To my understanding, you look up the spring that the cam card calls for and note the seat and open pressures that the spring specs out to be at its normal installed height. You then measure the installed height that you currently have, and you then select a spring that will give you the correct seat pressure at your installed height, and has enough spring rate to give you the correct open pressure that the cam calls for.

If the spring you find has the correct seat pressure at a slightly less installed height, you use shims to achieve the spring installed height you're after.
 

· Sit N' Spin
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1,345 Posts
Thanks guys..I got my block back yesterday and i'm gonna install the cam and one head and check the lift/coil bind clearance deal on cyl#1. Does that sound appropriate for a rookie?

Thanks
If you know the coil bind spec on the spring and the installed height, just subtract your valve lift spec from your installed height, then subtract the spring's coil bind spec from this number. If the difference between these two numbers is greater than 0.060", you're good on the coil bind.
 
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