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Max lift for spring question...

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Old 01-18-2006 | 04:33 PM
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Default Max lift for spring question...

Springs: Comp 977s
Installed height: 1.850 measured
Coil bind: 1.195

Can I run a .625" lift cam with this? Sounds like I should be able to...
Phil
Old 01-18-2006 | 04:40 PM
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Gonna be close...I think most people factor in a .060 fudge factor before coil bind...that puts it at

1.850-1.195-.060=.595

What about a 914? I'm looking at to use with my LS7 heads.

147 @ 1.85
rate 367
1.11 bind
max lift .680

1.850-1.110-.060 = .680 lift, 'safe'
Old 01-18-2006 | 05:36 PM
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I have heard from a few engine build to shim the spring to .040 to .060 from coil bind for better control of the valves. This is to help reduce with the spring harmonics and reduce valve float.

Manufactures seam to add a little fudge to coil bind number.
The best way is to manually place the springs in a vise and compress the spring all the way to coil bind with the seat and retainer in placed, then measure. That is the real coil bind measurement.
Old 01-18-2006 | 06:43 PM
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1.850" - .625" = 1.225
1.225 - 1.195 = .030"

Like stated above, most reccomend about .060" from coil bind to be safe.
Old 01-18-2006 | 06:49 PM
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Also you should never rely on the spring chart for final info. You really should check the springs with a spring travel setup. And really you should be checking them with the retainer in place because that usually changes things up a bit...sometimes as much as .010-..020.

Even doing this in the last year or so I have seen that Comp Spring chart be wrong several times. As a matter of fact you can go to various places for Comp info and see conflicting info.
Old 01-18-2006 | 07:33 PM
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Nope, those springs will last about a month like that.... been there done that.

You can't go over .600" lift without good quality spring wire and hope that it lives in a hyd roller setup.

SlickVert is on to something! Call up LSM and ask them how close to coil bind you run the L1000 Pro Stock style springs at 10,000rpm...

Bret




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