Packard Forum Index » Post-War (1946-54)

From what I understand:

It's not that values burn up themselves, it its the valves slamming into the seat and abrading them. The "lead" provides a "buffer effect" that reduces valve recession in the cast iron blocks/heads. A hardened value seat cures that as well. But this is typically only a problem in higher RPM motors and engines that run a hotter exhaust temps. The straight eights are pretty low rpm motors. I cant find anyone oh here that has reported a major problem with valve recession in their motors, and we switched over to Unleaded 20+ years ago.

Supposedly running cars on propane or natural gas causes even greater risk to valve recession because of the dry nature of the fuel.