Running .550 lift on a 1218 spring
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TECH Apprentice
Joined: Aug 2009
Posts: 303
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From: Louisiana
Running .550 lift on a 1218 spring Does anyone see a problem running PAC 1218 springs rated for .600 lift on a .553 lift camshaft?
Word is, a spring is happier if ran to advertised open height.
I wanted to run this spring instead of the GM LS spring for it’s stronger closed/seat pressure.
90 vs 130.
Thank you
Word is, a spring is happier if ran to advertised open height.
I wanted to run this spring instead of the GM LS spring for it’s stronger closed/seat pressure.
90 vs 130.
Thank you
TECH Enthusiast
Joined: May 2008
Posts: 645
Likes: 578
From: Carnation, WA
Those springs are supposedly 313 lbs/in. So if you shimmed them .050" extra, you'd have 145 lbs of seat pressure instead of 130. Maybe that's more than you want, but it'd let you work the spring harder.
That's assuming it even matters to the spring whether it's run at advertised height. I don't know the answer to that.
That's assuming it even matters to the spring whether it's run at advertised height. I don't know the answer to that.
The elgin cam guy told me it was better to have .025 extra spring vs running a .595 cam at .600 max lift spring thus i used pac 1219s .625 with a .575 lift cam. You can for sure see spring coil binding or maxing out when installing springs or even rotating the motor over with cam and springs installed no calve covers.
TECH Senior Member
Joined: Jun 2016
Posts: 22,303
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From: Central Cal.
Running springs with more lift capacity than the cam has isn't a problem, only if you will be winding high enough that you want to prevent harmonics that getting it close to coil bind would prevent.
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I have never seen a single incident of what you describe, although I do "in theory" see how it could happen. Is your opinion based on actual fact or theory?
Been running Howard springs (same as 1218) on a .556 custom cam for 5 years and 15psi no issue. I have 1218s on a summit stage 1 high lift cam which is .550 I think but only has idle time in the car since it’s not done yet but no issues with them so far.