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Re: Valve spring math
[Re: Uberpube]
#2866223
12/29/20 09:25 PM
12/29/20 09:25 PM
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Joined: Oct 2006
Posts: 1,264
New York, USA
Chargerfan68
pro stock
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pro stock
Joined: Oct 2006
Posts: 1,264
New York, USA
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You have .552” lift, so .552 x 420= 232 lbs
Installed ht = 1.950 @ 138 lbs.
So 138 + 232 = 370 lbs open pressure.
1.50 60Ft. , 10.75@ 127MPH Hauling 3900 LBS.
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Re: Valve spring math
[Re: Chargerfan68]
#2866226
12/29/20 09:30 PM
12/29/20 09:30 PM
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Joined: Nov 2013
Posts: 712
Southern Alberta
Uberpube
OP
super stock
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OP
super stock
Joined: Nov 2013
Posts: 712
Southern Alberta
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You have .552” lift, so .552 x 420= 232 lbs
Installed ht = 1.950 @ 138 lbs.
So 138 + 232 = 370 lbs open pressure. Thanks for explanation, think I should check it physically?
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Re: Valve spring math
[Re: Uberpube]
#2866232
12/29/20 09:48 PM
12/29/20 09:48 PM
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Joined: Oct 2007
Posts: 4,209
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,209
New York
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Even though the spring rate is accepted as linear (each .100" of lift requires the same pressure as any other), it's not really true.
As the spring compresses, the pitch is reduced which lowers the rate. Springs with steep pitch are affected more.
I would guess the difference is not significant.
Boffin Emeritus
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Re: Valve spring math
[Re: Uberpube]
#2866248
12/29/20 10:23 PM
12/29/20 10:23 PM
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Joined: Aug 2003
Posts: 43,241
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,241
Bend,OR USA
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You have .552” lift, so .552 x 420= 232 lbs
Installed ht = 1.950 @ 138 lbs.
So 138 + 232 = 370 lbs open pressure. Thanks for explanation, think I should check it physically? Absolutely   Never trust theory on race parts  Always measure and verify I've seen valve springs from the same set and manufacturer vary 30 lbs. on the seats and 60+ lbs. opened   I learned the hard way a long time ago to measure every part in any motor that you want to run good and last a long time when beating on them  Never ASS U ME
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Valve spring math
[Re: Uberpube]
#2866393
12/30/20 11:22 AM
12/30/20 11:22 AM
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Joined: Oct 2006
Posts: 1,264
New York, USA
Chargerfan68
pro stock
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pro stock
Joined: Oct 2006
Posts: 1,264
New York, USA
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I don't know anyone with the tool to do this, any suggestions on which checking tool to buy that will do the job for a decent price? Once I do this this set, the tool will probably hide in my tool cabinet for years. In that case, i would bring them to a competent machine shop and have them mcheck them and record the numbers. Should be a minimal fee for this. If it is something you will be doing often in future, i would buy a good spring tester. But they can be expensive.
1.50 60Ft. , 10.75@ 127MPH Hauling 3900 LBS.
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Re: Valve spring math
[Re: Uberpube]
#2866407
12/30/20 11:47 AM
12/30/20 11:47 AM
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Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
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I have Trickflow 270 61617802-C01heads with option 1 spring (roller cam spring) PAC spring tfs-16094
138lbs at 1.950 installed height
430lbs at 1.250 open
420lbs per inch rate.
The info for that spring in the instructions supplied with that head are incorrect. Look up the specs for the spring in the valve spring section of the TF website. The correct specs are listed there. You can also look them up on the PAC website. It’s a PAC 1294 spring.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
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Re: Valve spring math
[Re: Uberpube]
#2866677
12/30/20 07:24 PM
12/30/20 07:24 PM
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Joined: Mar 2011
Posts: 3,089
Michigan
A727Tflite
master
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master
Joined: Mar 2011
Posts: 3,089
Michigan
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Is the lbs rating of valve springs linear?
I have Morel street performance roller lifters with this rating:
Recommended Spring Pressure
100-180lbs Seat pressure
280-380lbs Open pressure
I have Trickflow 270 61617802-C01heads with option 1 spring (roller cam spring) PAC spring tfs-16094
138lbs at 1.950 installed height
430lbs at 1.250 open
420lbs per inch rate.
Gross valve lift is .552, is it as simple as .552x420=232 lbs open?
or do I need to test what the spring pressure actually is at .552?
Look up Hooke’s Law - used to this day. He states all springs are linear unless ..........
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Re: Valve spring math
[Re: A727Tflite]
#2866745
12/30/20 09:58 PM
12/30/20 09:58 PM
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Joined: Oct 2007
Posts: 4,209
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,209
New York
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all springs are linear unless... the pitch changes.
A 100 coil spring 10" long has almost no pitch change in .100" compression, a 10 coil spring has a lot.
Boffin Emeritus
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Re: Valve spring math
[Re: fast68plymouth]
#2866757
12/30/20 10:29 PM
12/30/20 10:29 PM
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Joined: Nov 2013
Posts: 712
Southern Alberta
Uberpube
OP
super stock
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OP
super stock
Joined: Nov 2013
Posts: 712
Southern Alberta
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I have Trickflow 270 61617802-C01heads with option 1 spring (roller cam spring) PAC spring tfs-16094
138lbs at 1.950 installed height
430lbs at 1.250 open
420lbs per inch rate.
The info for that spring in the instructions supplied with that head are incorrect. Look up the specs for the spring in the valve spring section of the TF website. The correct specs are listed there. You can also look them up on the PAC website. It’s a PAC 1294 spring. Using that info, I come out at 411 psi on the wallace racing calculator. Guess I will have to send Trickflow an email and ask them whats up... That's over by a bit on what the morel lifters are rated for. Guess I could buy the gauge just to verify that its indeed that spring as well. When I click on the replacement parts for that head number, it does indeed give that Trickflow valve part number with a different , higher spring rate. hmmmm, just when I thought I was in the clear.
Last edited by Uberpube; 12/30/20 10:29 PM.
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Re: Valve spring math
[Re: Uberpube]
#2866834
12/31/20 05:21 AM
12/31/20 05:21 AM
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Joined: May 2019
Posts: 713
Lake Villa Il
INTMD8
super stock
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super stock
Joined: May 2019
Posts: 713
Lake Villa Il
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Is the lbs rating of valve springs linear?
I have Morel street performance roller lifters with this rating:
Recommended Spring Pressure
100-180lbs Seat pressure
280-380lbs Open pressure
I find it amusing they have a spring pressure rating. 180 on the seat with 1.5 ratio rocker is 270 to the lifter. 180 on the seat with 1.7 rocker is 306 to the lifter. So on and so forth. Unless you specify a rocker ratio, max seat and open pressure in relation to the lifter can vary quite a bit.
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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Re: Valve spring math
[Re: Uberpube]
#2866894
12/31/20 11:07 AM
12/31/20 11:07 AM
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Joined: Oct 2007
Posts: 4,209
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,209
New York
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Which "calculator" to use doesn't matter, they all use the same method, it's just arithmetic.
Spring rate in psi = (open pressure - closed pressure) ÷ lift
800 - 300 ÷ .600 = 833
Boffin Emeritus
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Re: Valve spring math
[Re: INTMD8]
#2866910
12/31/20 11:34 AM
12/31/20 11:34 AM
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Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
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Guess I will have to send Trickflow an email and ask them whats up. They have different data depending on where you look. In one place the data agrees with the manufacturer..... and the other doesn’t. As someone who has actually tested those springs, as they come off the 240 and 270 heads...... I can tell you the numbers from the manufacturer are correct. Additionally.........As someone who has worked in this industry for 30 years I can you that...... incorrect info in catalogs and instruction sheets is not at all uncommon. If you really want to know what the spring loads for your springs are...... pull a few off and have them tested.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
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Re: Valve spring math
[Re: fast68plymouth]
#2875149
01/16/21 04:36 PM
01/16/21 04:36 PM
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Joined: Nov 2013
Posts: 712
Southern Alberta
Uberpube
OP
super stock
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OP
super stock
Joined: Nov 2013
Posts: 712
Southern Alberta
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Guess I will have to send Trickflow an email and ask them whats up. They have different data depending on where you look. In one place the data agrees with the manufacturer..... and the other doesn’t. As someone who has actually tested those springs, as they come off the 240 and 270 heads...... I can tell you the numbers from the manufacturer are correct. Additionally.........As someone who has worked in this industry for 30 years I can you that...... incorrect info in catalogs and instruction sheets is not at all uncommon. If you really want to know what the spring loads for your springs are...... pull a few off and have them tested. Reply from Trickflow:Response By Email (Cortez) (01/15/2021 09:52 AM) Hello, The correct specs are below 1.550" O.D. dual spring with damper (TFS-16094) 138 lbs. @ 1.950" installed height 430 lbs. @ 1.250" open 420 lbs. per inch rate .680" maximum lift I'm going to check the springs.....
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Re: Valve spring math
[Re: Uberpube]
#2875162
01/16/21 04:51 PM
01/16/21 04:51 PM
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Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
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Unless they no longer use a PAC 1294 for that spring, the specs “should be”:
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
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Re: Valve spring math
[Re: Uberpube]
#2875243
01/16/21 08:02 PM
01/16/21 08:02 PM
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Joined: Aug 2003
Posts: 43,241
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,241
Bend,OR USA
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Check all of them at the installed height for each spring for seat and open pressure and how close each one is away from coil bind. Make sure they are within + or- 5% on both ends and at least .060 from coil bind, shim as needed
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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