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Thanks,

I hear you on the over revving. I’m going to put a 7600-7700rpm chip in the limiter and shift it at 7200-7300 to make sure it doesn’t overrev, but I would like to stay off the limiter on nitrous for sure.
Are you saying that I can and should drop the installed height down from 2.1” with this spring, or that I should change out the springs?
I always ASSumed that the more clearance you had from coil bind the better? I learned something new tonight. Thanks for this.
I had no idea that I had way too much spring in this thing. I’m not a fan of using stiffer springs than necessary, and I know that a lot of people err on the stiffear side, which is just more stress on the valvetrain and robs a bit of power.
As most have said your over springed with a big dia. triple, a smaller dia double with the correct spring rates are possible but you already have your springs.
The spring info all manufacturers list are a starting point and a way to verify there spring rates ,coil bind, etc. IMO start with the coil bind 1.130 add your lift .836 and then .050-.060 for spring gap which comes up with your installed height which is how most quality spring manufacturers suggest to do. Set up at those gaps at full spring compressoin the gap would be in the middle of the spring and the ends will slightly be touching. Better spring control , when your running big gaps in the spring it could lose control of the valve easier causing spring surge/bouncing.
I dont know your cam supplier but they should have given you a spring rate or required spring pressure to control the specifics and their lobe design.
Is this a stainless valve or titanium?
You will likely need the other keepers as well as Scott has stated if using these spring which should be done before any height measurements to set up springs.
 

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Discussion Starter · #22 ·
As most have said your over springed with a big dia. triple, a smaller dia double with the correct spring rates are possible but you already have your springs.
The spring info all manufacturers list are a starting point and a way to verify there spring rates ,coil bind, etc. IMO start with the coil bind 1.130 add your lift .836 and then .050-.060 for spring gap which comes up with your installed height which is how most quality spring manufacturers suggest to do. Set up at those gaps at full spring compressoin the gap would be in the middle of the spring and the ends will slightly be touching. Better spring control , when your running big gaps in the spring it could lose control of the valve easier causing spring surge/bouncing.
I dont know your cam supplier but they should have given you a spring rate or required spring pressure to control the specifics and their lobe design.
Is this a stainless valve or titanium?
You will likely need the other keepers as well as Scott has stated if using these spring which should be done before any height measurements to set up springs.
Thanks. I had no idea I had too much spring. These are the springs that came on the heads when I got the motor from SRE in ‘08. I had bought these as a replacement set. The cam in that 565 motor was slightly smaller than the one in my new 582, so up until now I was actually thinking it might not be enough spring.
Both cams are custom SFO cams ground for SRE. I have both cam cards, and there’s no mention of recommended spring on either card.
The longer valves that Brodix installs in the 3XTR - O heads is what calls for a 2.10” installed height.The +.050 “ locks obviously add to that.
I’m running stainless 2.35 intake and 1.88 exhaust valves.
I was looking at the PSI DR425R dual coil spring which is 1.625” dia, 622# rate and has a seat pressure of 305# @ 2.05” installed height. Coil.bind on that spring is at 1.1”
So taking your approach of coil bind plus cam lift plus .060 clearance:
Intake valve: 1.1 + .836 + .060 = 1.996”.
Exhaust valve: 1.1 + .816 + .060 = 1.976“
So, by that method, a 2.00” installed height should be close to what I want, IF that spring is the suitable for my cam specs.
Do I have the calculus right?
 

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I have run the DR425R springs at 2.030" and 1.985" with .800" net lift on 2 engines and no issues. 150-160 grams intake weight. Get the optional polished ones if you want a little more potential life. Still a big diameter spring at 1.625"
 

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Discussion Starter · #24 ·
I have run the DR425R springs at 2.030" and 1.985" with .800" net lift on 2 engines and no issues. 150-160 grams intake weight. Get the optional polished ones if you want a little more potential life. Still a big diameter spring at 1.625"
Thanks. That’s very helpful. I know it’s still a bigger diameter spring, but I think I’ll be okay on clearance once the retainer moves down and away from the rocker.
Actually, I think that just changing the locks with these springs and retainers would get me the clearance I need, and that would put my installed height closer to where it needs to be.
So I’m thinking for now I’ll get a spring pressure tester and take Scott’s advice and pull the inner spring out, check coil bind and then calculate installed height from that and then see what seat pressure I have at that installed height and then decide whether I need to change out the springs and retainers now or not.
I’ll report back on here what I find out.

Thanks again to everyone for your advice, which is greatly appreciated.
 
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FWIW, I spun these dual springs to 11.5k RPM…

 

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Thanks again for all the advice. It is greatly appreciated.
I don’t actually have a lot of faith in comp springs, although I previously ran a set of these 948s in my old 565 without any issues.
I was thinking I needed this stiff of a spring due to running stainless valves?
I don’t have a problem changing the springs out, and would much prefer to run the right spring, and from what I read, PAC and PSI makes better springs?
I’m certain I can get .06” clearance just by changing the locks to standard height, but now I’m thinking I need to change the springs and installed height to optimize coil bind as well?
Thanks for the advice on pushrods. Believe or not, my previous setup was running these springs with .080” wall 3/8 diameter pushrods. I was planning to run 7/16 .165“ wall tapered P/Rs on the exhaust and at least a .135” 3/8” dia on the intake. But it looks like I need less spring and more pushrod?
Thanks again for the advice.
I've done several engines with big stainless valves and the pressures I quoted above, running in the mid to upper 7K range with no issues. Your 2.35 intake won't be a problem at that rpm. PAC and PSI are about the only springs I use these days. Comp gets their springs from several different suppliers. I wouldn't think their big triple is a bad spring so If you can get what you need out of it, I'd run it for now. If and when they give up the ghost, cross that bridge then. I would get an on-the-head spring checker so you can keep track of your pressures. Get a baseline when they're new and monitor any changes.
Pushrods are way important and way overlooked. The bigger the better. It's common where more spring pressure is added to try and control a problem caused by too-small of a pushrod so yes, bigger pushrods can lead to less spring pressure. You don't want the pushrod to be a secondary spring in the system.
 

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Discussion Starter · #27 ·
I've done several engines with big stainless valves and the pressures I quoted above, running in the mid to upper 7K range with no issues. Your 2.35 intake won't be a problem at that rpm. PAC and PSI are about the only springs I use these days. Comp gets their springs from several different suppliers. I wouldn't think their big triple is a bad spring so If you can get what you need out of it, I'd run it for now. If and when they give up the ghost, cross that bridge then. I would get an on-the-head spring checker so you can keep track of your pressures. Get a baseline when they're new and monitor any changes.
Pushrods are way important and way overlooked. The bigger the better. It's common where more spring pressure is added to try and control a problem caused by too-small of a pushrod so yes, bigger pushrods can lead to less spring pressure. You don't want the pushrod to be a secondary spring in the system.
Thanks very much for this, all of which makes total sense to me.
I think I’m going to run the springs I have now, with the inner spring removed, if that doesn’t drop the seat pressure below 280# at the correct installed height, per my previous post.
I’ll order an on-head spring pressure tester as well.
Thanks again for taking the time.
 
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"In the past, greater clearance was highly recommended, but current performance engine builders prefer a tighter clearance to coil bind as this helps dampen spring oscillation at high rpm which improves spring life and valve control. But this demands attention to detail."

How to Set Up a Cylinder Head (dartheads.com)

This was just a quick search on coil bind.

Have you asked the cam grinder what they recommend for a spring at your lift and RPM? Weights of components affect it also.
 
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Thanks. I had no idea I had too much spring. These are the springs that came on the heads when I got the motor from SRE in ‘08. I had bought these as a replacement set. The cam in that 565 motor was slightly smaller than the one in my new 582, so up until now I was actually thinking it might not be enough spring.
Both cams are custom SFO cams ground for SRE. I have both cam cards, and there’s no mention of recommended spring on either card.
The longer valves that Brodix installs in the 3XTR - O heads is what calls for a 2.10” installed height.The +.050 “ locks obviously add to that.
I’m running stainless 2.35 intake and 1.88 exhaust valves.
I was looking at the PSI DR425R dual coil spring which is 1.625” dia, 622# rate and has a seat pressure of 305# @ 2.05” installed height. Coil.bind on that spring is at 1.1”
So taking your approach of coil bind plus cam lift plus .060 clearance:
Intake valve: 1.1 + .836 + .060 = 1.996”.
Exhaust valve: 1.1 + .816 + .060 = 1.976“
So, by that method, a 2.00” installed height should be close to what I want, IF that spring is the suitable for my cam specs.
Do I have the calculus right?
Yes looks like your math is correct IF you change springs. If using the ones you have know already adj that formula to set correct spring height AFTER you drop the retainer height with differnt locks. Also you may want to get some finer shims to get your spring height correct preferably .050-.060 ranges , the spec you posted was good on the intake but leave your exhaust about .084in if both were set at 2.00.
Soooo get the spec height close as possible to needed because the extra adds to your .050-.060 in a +/- way.
 

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Discussion Starter · #31 ·
If you have inner spring locators that center up on the guides instead of outer spring cups that center up in the recess of the head castings, you might want to consider that. Removing inner springs could cause springs to move around?
Thanks. That’s a good point. But I do have spring cups that have an outer lip.
 

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Discussion Starter · #32 ·
Yes looks like your math is correct IF you change springs. If using the ones you have know already adj that formula to set correct spring height AFTER you drop the retainer height with differnt locks. Also you may want to get some finer shims to get your spring height correct preferably .050-.060 ranges , the spec you posted was good on the intake but leave your exhaust about .084in if both were set at 2.00.
Soooo get the spec height close as possible to needed because the extra adds to your .050-.060 in a +/- way.
Okay. Thanks. So, you’re saying I should shim the exhaust spring a bit more to keep the spring gap at max lift as close to .050-.060” as possible, correct?
I’m planning to order some more shims as well, so that I can get the installed height correct.
 

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Discussion Starter · #33 ·
"In the past, greater clearance was highly recommended, but current performance engine builders prefer a tighter clearance to coil bind as this helps dampen spring oscillation at high rpm which improves spring life and valve control. But this demands attention to detail."

How to Set Up a Cylinder Head (dartheads.com)

This was just a quick search on coil bind.

Have you asked the cam grinder what they recommend for a spring at your lift and RPM? Weights of components affect it also.
Thanks for the link. I’m going to watch that. I’ll also send SRE an email and ask them what they think I should use for springs. After all, much has changed since they built my original motor back in ‘08.
 

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Okay. Thanks. So, you’re saying I should shim the exhaust spring a bit more to keep the spring gap at max lift as close to .050-.060” as possible, correct?
I’m planning to order some more shims as well, so that I can get the installed height correct.
Correct get as close as possible since you have a split lift cam, the little things you do now will pay off later especially with a nitrous motor.
 

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Great video! I wish there was a spintron near me. It would be very interesting to see just how bad things were getting under the valve covers.

Throwing that valve open another .100 how is he not going into coil bind? I assume for this test the valve train is purposely setup wrong but what if you are setup at .060 and you still get this loft over the nose? I guess most guys just roll the dice on this but wow. Thanks for posting this.
 

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Great video! I wish there was a spintron near me. It would be very interesting to see just how bad things were getting under the valve covers.

Throwing that valve open another .100 how is he not going into coil bind? I assume for this test the valve train is purposely setup wrong but what if you are setup at .060 and you still get this loft over the nose? I guess most guys just roll the dice on this but wow. Thanks for posting this.
Went through some of this craziness with a friends turbo motor, SBF with a large turbo that sees 50psi boost @ 9000rpm. Valve train components were top of the line , cam was designed by a top cam manufacturer but damm if something didnt break in the valve train after every 2-3 passes which got old very quickly. After about 3 times doing this I talked to a different cam guy and sent him the cam to run on a cam doctor, he called and said this was the craziest/ harshest lobe he has ever seen and said the lobe was the problem so he ground a cam with his lobe and nearly the same specs and the car went faster BUT BEST OF ALL made it through a whole year with no problems and only basic valve adjustments
And yes it would have been into bind BUT it went well past it so I don't know were they had the springs set up/ obviously not at .060, bad cam lobe design and improper valvetrain set up may cause a BOOM. As you see the craziness starts at higher Rpm.
 

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Discussion Starter · #38 · (Edited)
That is a very informative video. BTR is an awesome company and Tooley is a very knowledgeable, stand up guy. Years ago I bought an LS3 cam kit from another vendor and that kit came with what I suspected was a BTR spring kit, with no literature except a cam card, and what appeared to be the wrong Ti retainers.
So after trying to contact the vendor, I called BTR and Brian himself answered the phone and he took the time to listen to me, then asked me to email him some pictures, which I did, and he then emailed me back to confirm that they were his springs, which the vendor bought in bulk and relabeled. He also confirmed that I had the right retainer. At that point I had not spent a dollar with BTR, but since then I’ve ordered a couple of cams from him and a bunch of other stuff. Anything I need for LS parts I buy from them, and they have been nothing but awesome people to deal with.
 

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Also saw a old Comp cam springs video from 3 years ago and he said on there high performance springs to run .060 min coil bind, that would put ya at 2.03 int / 2.01 ex spring height and net .064 from bind if using your old spring. PAC, PSI and everyone are all very close on specs but stick with whats called for.
 

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Okay. Thanks. So, you’re saying I should shim the exhaust spring a bit more to keep the spring gap at max lift as close to .050-.060” as possible, correct?
I’m planning to order some more shims as well, so that I can get the installed height correct.
Anywhere between .05 and >.100 off c/b is going to be fine. Your actual coil bind within that set is going to vary anywhere from .010-.020 so fighting for .010-.020" of c/b is really a waste of time. Just keep it under .100 and anything under .05 you're going to want to measure every spring. That's not necessary.
 
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