Setting valve springs close to coil bind - Chevelle Tech
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post #1 of 20 (permalink) Old Feb 17th, 17, 1:10 PM Thread Starter
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Setting valve springs close to coil bind

I keep hearing that it's ideal to set the valve spring close to coil bind (0.060-0.075), but how is that possible when dealing with low lift cam shafts?

I have a 1.964 install height (without shims), and a 0.520" cam. With most coil bind specs being in the 1.10 to 1.21 range, how would that be possible? I don't think I would want to run more than a 0.100 worth of shims.

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post #2 of 20 (permalink) Old Feb 17th, 17, 1:17 PM
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Re: Setting valve springs close to coil bind

I think you'll find seat and open spring pressure more important. If you tries to set it so you approached coil bind your spring pressure would be to high.

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post #3 of 20 (permalink) Old Feb 17th, 17, 1:25 PM
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Re: Setting valve springs close to coil bind

I think the coil bind specs you listed are probably the minimum you would want to run. Having more is certainly not going to hurt anything. The important thing, as stated above is having the correct installed spring height to produce the appropriate spring pressure for the camshaft you're using.

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post #4 of 20 (permalink) Old Feb 17th, 17, 1:44 PM
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Re: Setting valve springs close to coil bind

Chris,
With that small of a cam it really is not an issue. I think it is a lot more important when you have gigantic roller springs and big lift cams. The current thought in those cases is to have the spring about .050 from coil bind at full lift.

Like Troy said, seat pressure and open pressure are more important on most street and mild performance cams. Especially if it is not a roller. Roller cams can tolerate a lot more variation in spring pressures but flat tappet cams cannot.

You need to run whatever spring pressures your cam manufacturer recommends.

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post #5 of 20 (permalink) Old Feb 17th, 17, 1:54 PM Thread Starter
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Re: Setting valve springs close to coil bind

I agree about the pressures. I talked with PAC springs, and they said particularly with a beehive spring you want to install them to run close to coil bind. This reduces the spring vibrations I guess.

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post #6 of 20 (permalink) Old Feb 17th, 17, 2:13 PM
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Re: Setting valve springs close to coil bind

Is this a roller or flat tappet cam ?

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post #7 of 20 (permalink) Old Feb 17th, 17, 2:26 PM Thread Starter
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Re: Setting valve springs close to coil bind

Hydraulic Flat Tappet

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post #8 of 20 (permalink) Old Feb 17th, 17, 7:23 PM
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Re: Setting valve springs close to coil bind

On a flat tappet cam, I would run as low a spring pressure as possible.

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post #9 of 20 (permalink) Old Feb 17th, 17, 7:29 PM Thread Starter
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Re: Setting valve springs close to coil bind

Right now I am running Comp 924s. The way they were set up, it seems I only had 97# seat, and 277# open, when brand new. That's just way too low

I'd like to be in the 120-135# seat, and 310-330# open. If I could install 0.15-0.20" from coil bind, it would give me lots of options.

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post #10 of 20 (permalink) Old Feb 17th, 17, 7:51 PM
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Re: Setting valve springs close to coil bind

Quote:
Originally Posted by -SS454- View Post
Right now I am running Comp 924s. The way they were set up, it seems I only had 97# seat, and 277# open, when brand new. That's just way too low

I'd like to be in the 120-135# seat, and 310-330# open. If I could install 0.15-0.20" from coil bind, it would give me lots of options.
What's your installed height. Spec calls for 125# @ 1.880 installed height. And 315# @ 1.280 open. I think .015"-.020" is to tight probably want more travel to coil bind.

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post #11 of 20 (permalink) Old Feb 17th, 17, 9:00 PM Thread Starter
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Re: Setting valve springs close to coil bind

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Originally Posted by senna View Post
What's your installed height. Spec calls for 125# @ 1.880 installed height. And 315# @ 1.280 open. I think .015"-.020" is to tight probably want more travel to coil bind.
Install height without shims is 1.964

The 924s are 112@1.900 and 355@1.200

0.150 to 0.200, not 0.015-0.020. That would allow me to choose from a bunch of different springs, but it goes against the ideal 0.060-0.075 from coil bind.
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post #12 of 20 (permalink) Old Feb 17th, 17, 10:45 PM
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Re: Setting valve springs close to coil bind

Like Bill said, that's a mild cam. Factory installed BBC height was 1.88" Set them up between 1.88" and 1.90 and run it.

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post #13 of 20 (permalink) Old Feb 18th, 17, 7:57 PM
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Re: Setting valve springs close to coil bind

Chris,
Get a set of -50 valve locks. That will put you about 1.915, or put a .060 shim under them all and be done with it.

Unless you plan on turning the engine 6500 rpm on a regular basis, you are just plain overthinking this.

If you really want the extra pressure for some reason, put a .060 and a .015 shim under them. that will put you at about 1.885"

Either way you are nowhere near coil bind.

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post #14 of 20 (permalink) Old Feb 18th, 17, 11:44 PM Thread Starter
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Re: Setting valve springs close to coil bind

Quote:
Originally Posted by BillK View Post
Chris,
Get a set of -50 valve locks. That will put you about 1.915, or put a .060 shim under them all and be done with it.

Unless you plan on turning the engine 6500 rpm on a regular basis, you are just plain overthinking this.

If you really want the extra pressure for some reason, put a .060 and a .015 shim under them. that will put you at about 1.885"

Either way you are nowhere near coil bind.
You're probably right about over thinking this. I am not concerned about hitting coil bind, even if I go with a larger cam that has 0.554 lift. I am concerned with not setting up close enough to coil bind.

Right now I'm floating the valves past 5500, and I pretty much need it to hold to 6000. Not a big deal.

In any case, I'll get a locator for the bottom which will reduce the install height by 0.060 to 0.062, which will get me right in the ball park where I need to be.

If I could get a tool steel retainer for the 924s, I would be tempted just to use those springs again, as it's very light on the camshaft.

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post #15 of 20 (permalink) Old Feb 19th, 17, 2:20 AM
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Re: Setting valve springs close to coil bind

not always good to use drag car racing parts and techniques on a non-drag car.

You check all your valve springs after every 5 or 10 miles of driving?

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