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Discussion Starter #1
Was installing springs in my motor last night, and I’m confused by what I read for measuring distance to coil bind after installation.
First off, my springs measure okay by either method…but the method you see in the cam catalogs doesn’t seem correct to me:
http://www.lunatipower.com/Tech/Valvetrain/ValveSpringTech.aspx
This morning I grabbed an old valve spring and ran it down to coil bind = 1.170”
Then backed it off .060” (1.170 + .060 = 1.230) and measured the gaps between the coils. I could comfortably put a .020” feeler gauge between 3 coils, which makes complete sense
(.020 x 3coils = .060”)
I can force a .030” gauge between the coils, but I would have to force 2 coils apart with a screwdriver to ever get a .060” gauge in there…I doubt this is a good thing to try.
So next I relaxed the spring until I had .060” between the active coils. This resulted in a spring height of 1.345”.
So if I was checking the spring like the link shows, I would have to have a spring height of 1.345” at max lift…which means I would actually be 1.345-1.170 = .175” of total coil clearance from coil bind. That is almost 3 times the clearance when compared to the bench measuring method.
So which is correct? :smt102
 

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The mathematical way once you are positive of the actual coil bind.... so take coil bind + your clearance + NET lift = installed height.
 

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Discussion Starter #3
Thanks.
I was pretty sure the mathematical way was correct...part of me was paranoid that there was something I wasn't seeing...the other part was wondering why the hell they even tell you to measure the coil gap like the illustrations lol.
 

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a quick little side note here, ..

it's best to physically measure coil bind, sometimes the factory specs
aren't exactly right, but often close.

But something I wanted to point out, .. if you are measuring coil bind
with a spring checker, .. actually measure the coil bind height
and DO NOT use the height where pressure begins to spike !!
The pressure will start to sky rocket before actual coil bind, ..
and setting a spring up based on that can actually cause it to
go "nuttso" faster.

Had a few pro engine builders doing this and drove me crazy trying to help
with their valve train till I found this out.

curtis
 

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a quick little side note here, ..

it's best to physically measure coil bind, sometimes the factory specs
aren't exactly right, but often close.

But something I wanted to point out, .. if you are measuring coil bind
with a spring checker, .. actually measure the coil bind height
and DO NOT use the height where pressure begins to spike !!
The pressure will start to sky rocket before actual coil bind, ..
and setting a spring up based on that can actually cause it to
go "nuttso" faster.

Had a few pro engine builders doing this and drove me crazy trying to help
with their valve train till I found this out.

curtis
Very good point.
Even the highest quality springs out there can have wire diameter tollerance +/- .005. Multiply this by the number of coils, and you can quickly see it isn't cut and dry when setting up a target distance from solid (true coil bind).
 

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Very good point.
Even the highest quality springs out there can have wire diameter tollerance +/- .005. Multiply this by the number of coils, and you can quickly see it isn't cut and dry when setting up a target distance from solid (true coil bind).
Adding to Warp and Curtis' points:

I measure all my springs to see bind height variance, from part to part. In the last couple days I measured some springs for a common flat tappet deal and the coil bind heights varied by .020" from lowest to tallest spring. These weren't what I would call the highest of quality (not PSI or similar) but they are from one of the largest cam companies out there.

If you're going to do your own stuff make sure you measure EVERY SINGLE PART!!!

Tie this to the other discussion regarding what it costs to build an engine....
 

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Larry, keep in mind that if you are going to play around with valve lash you will be either adding or taking away coil bind clearance. What Curtis said regarding using a pressure checker drove me crazy for a while... I would check the springs for coil bind in the checker and measure when I got the "spike" in pressure then compress them solid off the checker and the distances would be different. Also, as Jay and Rob suggested, measure EACH spring. The PAC springs that you and I discussed before varied .040 from 1.138 to 1.178. Remind me at Indy and I will show you the measurements...
 

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Discussion Starter #8
I checked them and they do definitely vary.

I guess what I was wondering is why everyone publishes a method of checking clearance after installation that seems bogus.
 

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I find an arbor press makes it easy to measure the roller springs for bind height. I put a spring and retainer in the press with a 1/4" aluminum plate on top of the retainer, collapse the spring, and use verniers to measure between the bottom plate and top plate. It's amazing how far off some springs are from spec.
 

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And PLEASE always use a retainer when checking. I have seen a bunch of springs where the inner spring coil binds before the outer when using a retainer vs not.
 

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Ignore that picture. Its just wrong... If you're setting up for .060 to coil bind, there sure isnt going to be .060 between each coil!

If bind height were 1.14 and you set up for .060, the tightest youd run is 1.20, leaving you .060 from your coil bind spec of 1.14.

Thats total clearance. If you had .060 between each coil....youd need a mighty tall spring to make that work!

.060 is the sum of the gaps between all the coils, and if you would do the math on every spring out there looking at their closed, vs open, vs bind height.....youd see right away none of them are giving you specs for .060 between each coil, which is exactly what you saw by measuring up your springs.

A few cam companies have that particular picture on their website, and it kinda makes me laugh cause its all wrong. No worse than the some of the valvetrain companies that tell you that you "need" .xxx longer or shorter pushrods with their parts, making the less educated consumer think you dont actually have to measure for things such as pushrod length when your mixing and matching various components and putting it all together with heads or a block that may have the decks cut, even further changing the pr length required.

Keep doin it like youre doin it.
 

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We use the Power Technology Spring tester,its an arbor press with a load sensor and computer connection shows on screen and can print all the data and save info if desired,extremely sensitive and can print sheets of data for your customer and can do graphs that can be sent to camshaft and valve train software.Bill C.
 
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