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Author Topic:   valve spring testing question
Fastback
Journeyman

Posts: 28
From: Livonia,MI
Registered: Dec 2001

posted 01-08-2002 12:41 PM     Click Here to See the Profile for Fastback   Click Here to Email Fastback     Edit/Delete Message   Reply w/Quote
What is the correct way to test valve springs? I bought a valve spring tester made by Tavia and am getting different pressure readings with the same valve spring. If I test the spring at a height of 1.820 I get 105 pound reading. If I compress the spring to say 1.500 and then back down to my original 1.820 I now have 120 pound reading. Is this a problem with the gauge or is it that my 120 pound reading at 1.820 is because of the stored energy from compressing the spring?


Fastback

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Rustang1
Gearhead

Posts: 110
From:
Registered: Nov 2000

posted 01-08-2002 01:01 PM     Click Here to See the Profile for Rustang1   Click Here to Email Rustang1     Edit/Delete Message   Reply w/Quote
What is your method of compressing the spring and how are you measuring the height? Are you rechecking the height before and after you compress the spring beyond 1.820"?

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1968 Mustang,Clevor,C4
1969 Torino 351C 4spd
1978 F150 460 C6
1978 F150 351W C6

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Rustang1
Gearhead

Posts: 110
From:
Registered: Nov 2000

posted 01-08-2002 01:05 PM     Click Here to See the Profile for Rustang1   Click Here to Email Rustang1     Edit/Delete Message   Reply w/Quote
One more thought...I have a Tavia compressor too, when I get home tonight I'll look at it, but I think the base that the spring rests against is free to rotate. When you compress a spring it will wind up a little like a screw. If this is happening, you'll probably get inconsistent readings.

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1968 Mustang,Clevor,C4
1969 Torino 351C 4spd
1978 F150 460 C6
1978 F150 351W C6

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Just Strokin
Gearhead

Posts: 754
From: Tuscaloosa, Alabama
Registered: Dec 2001

posted 01-08-2002 01:52 PM     Click Here to See the Profile for Just Strokin   Click Here to Email Just Strokin     Edit/Delete Message   Reply w/Quote
Have always heard that you should measure the spring with a retainer on it, but the height is just the spring. Is this the way you are measuring the pressure?

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Fastback
Journeyman

Posts: 28
From: Livonia,MI
Registered: Dec 2001

posted 01-09-2002 05:37 PM     Click Here to See the Profile for Fastback   Click Here to Email Fastback     Edit/Delete Message   Reply w/Quote
I am using a vise to compress the valve spring and tester. I am using the retainer with the spring and measuring the spring with a set of calipers once I compress the spring to my installed height which is 1.820. Every time I compress the past 1.820 and then back down to my 1.820, my second reading is always much higher.

Fastback

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Moneymaker
Administrator

Posts: 27499
From: Lyons, IL, USA
Registered: May 99

posted 01-10-2002 11:47 AM     Click Here to See the Profile for Moneymaker   Click Here to Email Moneymaker     Edit/Delete Message   Reply w/Quote
It's probably the slack in your vise.

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Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
US Class Nationals link

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Rory McNeil
Gearhead

Posts: 1687
From: Surrey, B.C. Canada
Registered: Nov 2000

posted 01-10-2002 12:29 PM     Click Here to See the Profile for Rory McNeil   Click Here to Email Rory McNeil     Edit/Delete Message   Reply w/Quote
You only need to check the springs with the retainers if you are using double or triple springs. This is because the inner springs are loaded by the steps on the bottom of the retainer. I have used my buddys Rimac valve spring tester, very consistent readings.

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78 Fairmont 428 4 speed [email protected]
80 Fairmont 302 5 speed [email protected]
85 Mustang NHRA Stocker under construction, 302 5 speed

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Fastback
Journeyman

Posts: 28
From: Livonia,MI
Registered: Dec 2001

posted 01-10-2002 05:33 PM     Click Here to See the Profile for Fastback   Click Here to Email Fastback     Edit/Delete Message   Reply w/Quote
How could it be the slack in my vise causing my inconsistant readings if I am remeasuring the valve spring at 1.820 both times and it is always more on the decompressing of the spring?

Thanks,

Fastback

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Moneymaker
Administrator

Posts: 27499
From: Lyons, IL, USA
Registered: May 99

posted 01-10-2002 11:37 PM     Click Here to See the Profile for Moneymaker   Click Here to Email Moneymaker     Edit/Delete Message   Reply w/Quote
I have never been able to get accurate readings using a vise and a clip on type tool. The teeth in the vise gear are so large that there is a fair amount of play. Even though you are measuring at 1.820 each time I can guarantee that the vise has not opened and closed exactly the same distance. The tollerances are just too loose.

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Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
US Class Nationals link

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