Valve Spring Identification

['76 911S 3.0]

A question for the brain trust, I purchased a set of heads a while back and am curious if anyone can ID these valve springs for me. My OE springs in my other heads do not have these markings on them (albeit the text is a bit tough to read) but was curious if anyone has any knowledge on these. It appears there may be a Porsche triangle logo on the end of the part number but I am not entirely sure. I have also included a measurement of the outer spring thickness (if that helps any).

From what I can see, the part number appears to be something like: HF1C73 (maybe?)

Appreciate any input or insight. I think perhaps the best way to ID would be to remove and measure the pressure at installed height spec.

[stownsen914]

Not sure if my information is the best, but since no one else responded ... a former Porsche engine builder and racer once told me once that springs with the white lettering on them were the early S versions. I can't confirm that, or what exactly what (if anything) made early S springs different from other 911 springs.

[faapgar]

Valve spring mysteries.Porsche used the same springs for everything 65 & up.The only difference was the 911S motors with a real S cam timed at 5.0-5.4 at overlap.The race motors used the same part but were more closely picked.Think Neil Harvey at parts.He would look through as many as he needed to find a close set.All the springs I checked the factory motors were very close.Also 3.0 RSR motors were 10:3 CR for customers & factory were 12:5 to 1.Ciao