One additional observation:
The valve I show in the photos is marked "upside down" relative to the way it is installed in the engine. Not important, since the markings are covered when it's installed. The two valves that Brian shared in his post (referenced above) are also marked in this orientation. However, I have seen photos with valves marked the other way. See attached photos, both from WCCC. One valve is clearly used, but is it assembly line or service part? The other photo is a reproduction. The repro has a larger chamfer at the bottom end where it goes into the valve cover. The used WCCC one also looks like it may have a larger chamfer, but I cannot say for sure. And neither photo shows if the SSC logo is present.
A couple of possibilities come to mind:
1) The direction of the markings has no meaning. Perhaps they were randomly inserted one way or another into the marking die.
2) The direction changed at some point in time.
3) More than one supplier was used, and they marked valves differently.
Regarding possibility number three: SSC's patent was issued in 1966. For other manufacturers to make the valves without infringing on SSC's patent, SSC would have had to grant permission. Seems unlikely, but that is entirely a hunch. Have other manufacturer logos been observed on PCV valves of this type within this general timeframe?
