[rotorwrench]

I was interpreting that wrong although it wasn't too clear about the clearance they were mentioning but the .010" makes sense for stem to tappet clearance. It's way too much for stem to guide clearance for sure. A lot of folks think stainless steel is harder then carbon steel. Structurally, it's certainly hard enough but the surface is softer than steel and that's where the galling comes from. I guess with modern computer aided machines, it's cheaper to machine the whole valve but that seems kind of wasteful to me. That was the reason Charles Thompson developed the welding process.

With the aircraft engines, we used stainless stem valves for a while but they had to have the bronze guides due to galling. They went back to steel stems and high chrome steel guides and that works very well with minimal wear.

Flathead V8 engines have had some valve stems gall using the new all stainless valves. I'm not sure why they just don't weld them like they did for 80 years or so with no real problems. That way they could have stainless heads but steel stems. Ford used that type for exhausts and all steel valves for intakes and they worked just fine. Most flathead V8s had cast iron guides and they worked just fine whether two piece or solid depending on stem types. Times have certainly changed.