#1  
Old 08-13-2020, 09:49 PM
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Default Cutting Valve Spring Seats on 6X heads

First off I don't like to see shims under the valve springs get all chewed up from the springs hammering them. I want to cut the valve spring pockets on my 6X heads to a 1.86 installed height so after I put the spring locator in I have an installed height of 1.8. I have RAV length valves and I would need to cut about .043 off the seats to achieve the 1.86 installed height. I don't know if these spring seats have already been cut in the past so I am concerned about cutting too deep and ruining the heads. Does anyone know how far you can safely cut the spring seats on 6X-8 heads?

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Old 08-13-2020, 10:20 PM
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Not trying to side track but I am a little confused by your question. If I understand you do not want to use any shims and would like to just use spring locator cups instead. The cups are generally .060-.090" thick which is too thick and would give you less installed height than you want? If that's correct, I would buy .060 locators, measure the installed height first and cut each spring the amount you want for installed height. I can't imagine cutting .040" being an issue. A simpler plan which works very well and even cost less is to use spring shims, (VSI) that are hardened. They are usually blue or black in color and are very hard. I have never seen a spring tear into the surface even with seat pressures over 350 lbs. They have a HP sufix after the part number. That way, you don't have to cut the spring seats and the HP shims are available in .015", .030.", and .060" for fine tuning each spring location. Good luck

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Old 08-14-2020, 05:30 AM
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As posted above, if you are using the needed high performance hardened spring shims you should have no ware issues but for what might be caused by not prepping the top and bottom of each inner and outer spring for no sharp edeges.

Another possibility that can be in conjunction with the above is that they are loosing control of there own mass at a rpm well below valve float, or that they are flat out allowing the valves to float.

Valve float can be seen by ware marks in the keeper groove.

The above two conditions are they only thing that will put ware into hardened spring shims other then no oil.

Also there is plenty of meat in the roof of a 6X head if it has not been ported heavily to cut it your needed .060", which is the way I would go.

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Old 08-14-2020, 10:21 AM
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Well the ports have been ported heavily 265 @ 28 but the way I am going the most I would need to cut one pocket would be .018 the rest between .002 and .006. This would put me at a IH of 1.835 -.06 for the locator and I would be 1.775 IH. I am thinking of using the Crane 99893 spring with an IH of 1.775 on the seat and intake lift of .515 be at 1.26 and exhaust lift of .530 be at 1.245. What I don't know is how to figure what the spring pressures would be at those heights.

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Old 08-14-2020, 11:04 AM
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I would double check your spring selection. I use those springs myself, and they're good IMO. However, I have over .600 lift. You're pressures will be something more than 140 maybe more than 150 seat. But check out how far away from coil bind you will be at .515 lift, I think it will be a lot. Steve C has posted some good info in the past about the instability effects of running springs in this manner. IMO you may wanna look at this more closely.

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Old 08-14-2020, 12:15 PM
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Scott, thanks for the info .
Pressure at installed height would be 158
@ max lift 360
Intake lift is .515 and Exhaust is .530. At max lift on the exhaust it will be .165 from coil bind. Are you saying I need to be closer to coil bind or it may have instability? Just when I thought I had it all figured out.

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Old 08-14-2020, 12:53 PM
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I'm not saying it, but it has been said... Yes too far away can have issues. Search for posts by Steve C on valvesprings. He has posted some info from experts.

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Old 08-14-2020, 01:10 PM
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I always wonder if our relatively low RPM (6,500 or so) even gets close to any harmonic action where dampening by coil contact is necessary. Most of the videos I've seen seems like things don't go haywire until about 8k. The 99893 is still my go-to spring for a lot of the builds and Have used it with shorter lift cams without a problem. I know that Dave Bisschop was using it on most of his daily builds, but don't know if he still does. My range of installed valve lifts with these springs range from about a high of .626 to a mild .560 without any problems.

Back in 1985 we sliced up a 670 head prior to cutting the seats and there was a massive amount of metal under them, and we did a .120" cut on the good heads and ran a solid cam and triple springs for years. Those heads are still around with the lighter pressure Crane springs on my street car. Unfortunately apples to oranges going over to 6X heads.

I think I would cut for 1.8" installed height including the .060" locator and then shim to whatever you need. Memory is that I only needed to go to mid 1.780's for 160 pounds on some sets.

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Last edited by lust4speed; 08-14-2020 at 01:16 PM.
  #9  
Old 08-14-2020, 02:31 PM
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Thanks Mick, this is the first time setting up my own heads so I am learning a lot. My only concern is cutting into the heads that deep as these heads were pretty much max ported and I fear ruining them. My highest spring perch is currently at 1.817 and my lowest is at 1.868. I would need to cut .043 from the highest perch and I have now way to know if I have enough material to do that. Is there a way to measure how much material I have to work with or are you saying cutting .043 is perfectly safe. Then if I did that I would need to find another spring.

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Old 08-14-2020, 03:09 PM
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I don’t think you would hit the intake port. The emission port is in between the spring perch and the intake port roof on a 6x. The boss underneath the spring seat is pretty thick.
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  #11  
Old 08-14-2020, 03:25 PM
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First, I WOULD NOT run the spring pressure that Lunati states with their recommended springs for the Voodoo cams on their website. Probably based on a factory installed heights and or spring diameters. Sort of like Comp that just regurgitates the use of the 995 spring !

Sort of related, not necessarily as a spring recommendation here but Dave Bisschop will typically use the Crane 99893 spring for the Old Faithful roller cam, he said they are typically 145-150 @ 1.800 installed height based on his spring tester. Certainly I would run at least that much pressure as a minimum in light of it being a Voodoo lobe. Also keep in mind that 150 lbs would be after run in when the spring has lost some of its initial pressure. AND THEY WILL LOSE PRESSURE.

I've posted what Paul Carter suggests for Voodoo Hyd flat tappet springs, he probably has the most experience with Voodoo cams than any on PY, including dyno time. I value his opinion. But off the top of my head I cannot recall how much he has stated on Voodoo hyd rollers. Do a search under gtofreek his user name. Or call him, he is a super nice guy.

But I've seen it stated here, "Paul C and others recommend 160 seat/360-400 open with a roller cam and conventional dual spring w/dampener setup."
This was in conjunction with a Voodoo lobe.

Not related to pressure but within a thread involving a Voodoo hydraulic flat tappet lobe Paul Carter suggested to keep the coil bind distance under 0.100" for the application in question. He might suggest the same on Voodoo rollers because of their intensity.

I've posted this one before....

"Depending on the intended use and the spring and cam-lobe design, coil-bind safety margins can now vary from 0.015 to 0.120 inch, with tighter numbers predominating on very stiff valvetrains. Anything more than 0.150 inch may cause spring surge, which can greatly reduce the available spring load needed to close the valve."

https://www.hotrod.com/articles/how-...arance-is-safe.


.

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Old 08-14-2020, 06:26 PM
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"For clarification we install the 99893 springs at 1.800-1.820" installed height with the OF cam. Steve Crane actually rates the spring for small solid roller use as well with a 1.750" installed height. We've experimented with many springs over the years and the 99893 has worked well for us over the last 10+ years with hundreds of sets in use in many street/strip combinations, with 1.65 rockers it puts us in the ideal .060-.120" range away from coil bind."
Dave Bisschop / 2011


.

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Old 08-14-2020, 09:19 PM
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Steve I appreciate all the reference material I have read everything but I still don't have a spring. The Old Faithful has a lot more lift than the Lunati 20510711 I can get the seat and open pressure in the correct range but it's still .165 shy of coil bind.

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Old 08-14-2020, 10:07 PM
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0.165" is a lot from coil bind, I would tighten that up a bit to decrease it to a max of 0.100". I shoot for 0.070" to 0.080".

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Old 08-14-2020, 10:13 PM
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Mine is around .080 as well, with the 99893 springs.

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Old 08-14-2020, 10:38 PM
Steve C. Steve C. is offline
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Comp 985 spring ?

1.430" O.D.
Rated 165 at 1.750"
1.150 coil bind
366 rate
Dual w/damper


.

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Old 08-14-2020, 11:29 PM
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If I went with a 1.75 IH that would give me 165 lb. on the seat and a little over 350 lb. open. At max lift on the intake it would be .085 shy of coil bind and on the exhaust .07. I think that's in the ball park. Thank you Steve much appreciated.

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Old 08-15-2020, 09:21 AM
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The on line Comp catalog spring chart indicates the 985 spring has 146 lbs at 1.800" lift. If I understand it correctly your proposed revised installed height will be closer to that 1.800". I only mentioned the 1.750 because it is 'rated' at that height.


.

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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 )
Old information here:
http://www.hotrod.com/articles/0712p...tiac-trans-am/

Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine)
5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension
https://www.youtube.com/watch?v=qDoJnIP3HgE

Last edited by Steve C.; 08-15-2020 at 09:40 AM.
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Old 08-15-2020, 10:55 AM
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Steve, If I end up using that spring I would change the installed height to 1.75 or maybe even a little less because you have to take in account the spring pressure will drop some after a few cycles and the springs may be not be the exact number in the catalog. If I ran a 1.75 IH I would have 165 on the seat and 340.51 at max lift on the intake valve and I sure don't want to go lower than 140 lb. at max lift. If I went with a 1.775 IH that would give me 174.15 on the seat and 355.15 at max lift on the intake. I like the additional pressure at the peak but not sure if 174 would be too much on the seat. Anyhow I don't think it would be prudent to have an IH of 1.8 with this spring for my application. Another consideration I have been thinking about is since the exhaust valve is lighter but at the same time has .015 more lift would it be prudent to run lower spring pressure on the exhaust valve?

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Old 08-15-2020, 11:56 AM
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Just a fwiw, it would be most interesting to make a phone call and try to get a hold of a Lunati tech rep who is somewhat familiar with Voodoo hyd roller lobes used in conjunction with a Pontiac valvetrain mass. Then ask him what he recommends for a spring pressure. Again not just stating from their catalog recommendations.

From the Lunati catalog, two springs stated for the 20510711 Voodoo cam:

73195 spring / dual
Rated 115 lbs at 1.700"
1.050 coil bind

74895 / Beehive
Rated 137 lbs at 1.700"
1.040 coil bind.

Obvious a lower pressure at a higher installed height and further from coil bind at max valve lift. But even installed at 1.700" I don't think I would want to run a Voodoo hyd roller lobe with 115 lbs spring pressure. This knowing that Paul Carter with actual dyno experience has recommended 130-135 lbs using a 30 degree valve seat on a Voodoo hyd flat tappet cam.


.

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Old information here:
http://www.hotrod.com/articles/0712p...tiac-trans-am/

Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine)
5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension
https://www.youtube.com/watch?v=qDoJnIP3HgE
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