Valve springs - can you tell visually if they are stock or stronger?

[kenikh]

Here is a valve spring off of my bench motor, still in the head. I will remove them soon to measure if they are in spec, but is there any way to tell if they are higher spec than stock without testing their tension?

[Henry Schmidt]

Porsche factory springs are the only spring that have a progressive winding. tighter at one end than the other.
If your spring has a progressive winding it is a factory spring. If it is not progressive it is an after market spring.

The spring in your picture looks progressive.

[kenikh]

I can't really tell if these are progressively wound or not; the springs are too small, unlike shocks. I will say in looking at them the coil gaps look pretty uniform.

I should be able to take a caliper and measure the outer coil gaps to confirm. Would this be a reliable way to check or is the only real way to check with a valve spring tester?

[Henry Schmidt]

Just look more closely at the spring. I may be mistaken (rarely happens ) but that spring looks progressive to me.

Look at the ends of the spring where they are ground flat. The angle of the coils at that point look different.
Coils closer together at one end.

[ChrisBennet]

Are they blue-ish? My AASCO valve springs are blueish.
-Chris

[kenikh]

They are indeed bluish. Henry, I'll take a closer look when I get home to confirm the details you were looking at.