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Testing: Valvespring spring rates!

36251 Views 40 Replies 30 Participants Last post by  Prymer
With this being a technical forum, we felt like it would be a good idea to show how to test valve spring pressure at both open and closed heights. Testing is a simple procedure but provides insight into a crucial and often overlooked component of the cylinder head.

The installed height of a valve spring is the length of the spring when it is installed on the head with the valves closed. It is important to differentiate between the advertised installed height and actual installed height. The most common advertised install height is 40.4mm or 1.5905 inches. This does not always translate into the actual installed height on a cylinder head. It can vary up and down based on a variety of factors including wear, manufacturing tolerances, and modification. These heights are measured by the spring only, so you have to factor in the thickness of the retainer as well as the spring base when it comes to setting your spring tester.

First you will need one of these:

A spring pressure tester is a simple tool. The spring is placed between the plates and the lever is used to compress the spring. The amount of forced exerted on the lower plate is shown on the scale needle.

Next, set the stop to the installed height of the valve spring. This limits the travel of the spring tester in order to provide an accurate measurement. A set of digital calipers is used to accurately set the stop at 40.4mm.

The next step is very simple. Place spring (with base and retainer) into the spring tester, and pull the lever. Be sure to take note of the pressure before moving onto the next spring.

The next step is to set the stop for the “open” position. In these tests we used an open lift of 0.520” The .520" lift number is just an arbitrary number we used for this example as many after market cams are around the .520 lift mark. Our KSi Cams are .535" lift.

Then place the spring assembly back into the tester and pull hard. Once again make sure you take note of the pressure.

Here is a list of some of the common valve springs people are using. Each of these measurements was done with the spring’s corresponding retainers and spring bases.

Supertech 1020D Valvesprings and Retainers kit
  • 96-97lbs on the seat (installed)
  • 287-288lbs open at .520" Lift
  • Max lift .655

GO Power Dual Springs and Titanium Retainers kit
  • 87-88lbs on the seat (installed)
  • 239-240lbs open at .520" Lift
  • Max lift .665

Skunk2 Pro Series Dual springs and Retainers
  • 73-74lbs on the seat (installed)
  • 235-236lbs open at .520" Lift
  • Max lift .660

Eibach 20411.216 Dual Springs and Titanium Retainers
  • 85-86lbs on the seat (installed)
  • 235-236lbs open at .520" Lift
  • Max lift .560

Stock 2006+ Civic Si Intake
  • 55lbs on the seat (installed)
  • 165lbs open at .500" Lift
  • Max lift .500

Stock 2006+ Civic Si Exhaust
  • 55lbs on the seat (installed)
  • 160lbs open at .500" Lift
  • Max lift .500

The Skunk2 and Eibach combos were tested in 2008. The GO Power and Supertech were re-tested last week.

If you would like, we can try and obtain and test other springs that people might be interested in.
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H1021D is 120 lbs @ 1.590 even though it says 95 on the package. Its important to realize most of these heads are really at 1.620-1.630 so the advertized spring rate only applies if it is shimmed and setup to reflect that. Most people just put in the spring bases that are supplied and don't check installed height.

Ferrea is 95 @ 1.590
4 Piston Endurance 105 installed max lift .600
4 Piston IRL 115 installed max lift .600
4 Piston Pro Stock Single 130 installed max lift .670

I tested Skunk Pro recently when I installed them in a customer head and they were around 100?? I'm going off memory.

This is all on my pressure tester, and I check it with calibration springs so its pretty close.
skunk2 has "upgraded" and "pro"

Do you know the difference in pressure for those?
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