2350 fuel pump tappets

[Hammerhead]

(06-09-2017 )simon999 Wrote:  The new ones blunt, the old ones pressed in flat.

Ok with that pic I can see that the outside circumference is chamfered, and probably conforms to the pump bore. Also the recessed ring that looks like an O-ring groove is actually an oil retaining channel that should hold more than sufficient amounts of oil to prevent hard contact scoring of the bore.
I agree that this would not be my preference, and definitaly not how I'd design it...which is why I'm not an engineer. I agree with Nalio that free floating pins should have some form of "capture" system to eliminate the risk of bore damage. My personal preference is teflon buttons. They don't fail, they don't come out accidentally or from vibration, and they don't contaminate anything. Every hot rod or dragster motor I've built, that's all I use. Unlike snap rings or circlips, I've never had or seen one fail yet.