The valve stems are textured - not smooth. I imagine this is to help lubricate between the guides and stems...? - it allows a film of oil to remain.

Can a valve stem seal ever truly be designed with the sole purpose of restricting all oil from entering the 'interstitial zone'?

As nature would have it, and as you mentioned, heat is going to cause the most harm w/respect to the stems and the guides; and the exhaust valves are all the more critical to keep sealed. The two engines of this era I have dismantled both had clearance primarily on the exhaust valves. Easily explained by heat, but, surely, exacerbated by friction. How can we make claims against burnt oil? I have some valves laying around.


the reciprocating engine is truly outdated.

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