Valve spring colors?

I have two new sets of valve springs and one used set. Each set has a different color paint on them. One set blue, one set cream and the used set red. Are they painted as a matched set or do they vary in rate? I do have a spring tester available an hour away and may compare them sometime. Just wondering if anyone has a answer for this?

I don’t know if this helps, but S3 XJ6 springs have a blue stripe. I should have other springs I can check. I know I have a new in the box set of V12 springs at the shop.

The one new set had BL box yet and by part number fits all xk 6 cylinder engines. Those are the blue set. The red came out of a 3.8 head.
The cream are new but out of original packing and came with a disassembled 3.8.

You don’t need fancy fixtures to do spring calcs. See sketch.

  1. Measure the unloaded length of the spring. This is Xo.

  2. Place spring under midpoint of the bar.

  3. Hang known weight (W) from end of bar.

  4. Measure the compressed length of the spring. This is Xf.

  5. We can calculate the static resistance of spring, F, from Fl = W2l, therefore F = 2W

  6. The spring rate is equal to F/(Xo - Xf)


Thanks! I have an actual spring measuring tool available to my use. Just curious if the color meant anything.

This is a new set of C14591 springs. Orange (or red) stripe. I believe this part number is for a V12.