How do you test valve springs for their rate and their remaining life span?

[Kern Dog]

I'm contemplating a switch to a roller cam in my car and I've wondered about the springs.
How does one determine if a valve spring is still good and what the rate of it is?

A Google search turned up this...
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To test the rate of a valve spring in an engine, you use a specialized tool called a "valve spring tester" which measures the pressure exerted by the spring at different compression heights, allowing you to determine its rate by comparing the applied force to the amount of valve lift; essentially, you remove the spring from the engine, place it in the tester, compress it to specific heights, and record the corresponding pressure readings to calculate the spring rate.

Key points about testing a valve spring:

• Specialized tool:
  A dedicated valve spring tester is required to accurately measure the pressure at different compression heights.
  
  
• Spring removal:
  Most testing methods involve removing the valve spring from the engine cylinder head.
  
  
• Compression measurement:
  The tester compresses the spring to specific valve lift heights, while recording the corresponding force exerted.
  
  
• Calculation:
  The spring rate is calculated by dividing the measured force by the valve lift at that point.
  

Important considerations:

• Manufacturer specifications:
  Always compare your measured spring rate to the manufacturer's recommended specifications for your engine and camshaft.
  
  
• Installed height:
  Ensure you measure the spring rate at the correct installed height, which is the distance between the valve seat and the retainer when the valve is fully closed.
  
  
• Coil bind check:
  Check for coil bind, which occurs when the spring coils touch each other at full compression, as this can damage the spring.
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  Is this spring checker something that a machine shop usually has?
  

 

[33 IMP]

If it's a decent engine shop, yes.
I bought a leakdown tester/spring tester combo several years back. It was to be used in a vice. It worked pretty good. They are available for home use, but are about three times as expensive as when I bought mine.
I loaned it out, never got it back.
A REAL spring tester usually found in a machine shop is a fairly expensive tool.
A Rimac spring tester is the industry standard, about $1000.
You can probably find a home-use tool for a couple hundred The combo I bought was under a hundred bucks.

 

[dvw]

I bought a 66836 ($177) Proform digital with a installed height mic attached. After a few tries you get the hang of it. You can tgen measure pressure at your exact installed height to the pound. It will repeat time after time. They also sell it non digital, 668334 ($73). Checked it against a $1000 Rimac tester. 13 springs measured exactly the same to the pound. The other 3 springs were within 3%. Plenty close enough. I've bought plenty of Proform engine building tools. Are the the top of the line? No. But for someone that only builds a few engines a year they serve the purpose with decent acuracy.
Doug

 

[Rebelrouser]

Just from my experience, buy a cheap valve spring tester. check your springs when new, seat pressure and open pressure. On retesting if there is more than 10% difference between your baseline buy new ones.

 

[69Bee]

I'm contemplating a switch to a roller cam in my car and I've wondered about the springs.
How does one determine if a valve spring is still good and what the rate of it is?

A Google search turned up this...
_______________________________________________________________________________________________________________________________________

To test the rate of a valve spring in an engine, you use a specialized tool called a "valve spring tester" which measures the pressure exerted by the spring at different compression heights, allowing you to determine its rate by comparing the applied force to the amount of valve lift; essentially, you remove the spring from the engine, place it in the tester, compress it to specific heights, and record the corresponding pressure readings to calculate the spring rate.

Key points about testing a valve spring:

• Specialized tool:
  A dedicated valve spring tester is required to accurately measure the pressure at different compression heights.
  
  
• Spring removal:
  Most testing methods involve removing the valve spring from the engine cylinder head.
  
  
• Compression measurement:
  The tester compresses the spring to specific valve lift heights, while recording the corresponding force exerted.
  
  
• Calculation:
  The spring rate is calculated by dividing the measured force by the valve lift at that point.

Important considerations:

• Manufacturer specifications:
  Always compare your measured spring rate to the manufacturer's recommended specifications for your engine and camshaft.
  
  
• Installed height:
  Ensure you measure the spring rate at the correct installed height, which is the distance between the valve seat and the retainer when the valve is fully closed.
  
  
• Coil bind check:
  Check for coil bind, which occurs when the spring coils touch each other at full compression, as this can damage the spring.
• 
  
• ______________________________________________________________________________________________________________________________________
• 
  Is this spring checker something that a machine shop usually has?

A roller cam has different lift #'s than a flat tappet cam, and the lobe ramps are usually more aggressive too. Get the springs recommended by the cam manufacturer for that specific cam you want.

Spring Tester...

 

[Thunderdan]

Having a good idea of the current spring rate will be very useful, but if you're using your existing FT springs then they aren't anywhere near strong enough for a roller cam that you're considering, let alone with hydraulic roller lifters as these lifters are *much* heavier than factory ones so replacements will be necessary. Unless you want valve float at 3K rpm.

 

[72redbird]

Something else to take into consideration is the diameter of the spring. Especially if going to a more aggressive profile. The diameter of the spring helps keep it cooler, so it does not get hot and break down. This was a very expensive, and important lesson that I learned from the gentleman named Harold that used to own Ultradyne Cams.