coaster wrote: ↑19 Oct 2021, 21:37
Just the seats, guides are pretty cheap, not worth making and i can live with bronze.
Copper is strange stuff, its soft and yet if its struck in a flywheel press it wears the machinery at moderate pace.
It seems a natural choice for a seat and its heat transfer properties also.
well .... copper beryllium isn't much like copper
(iirc copper isn't hardenable by heat treatment)
it is/was also called beryllium bronze or spring copper
(older type bronzes may or not have had a substantial tin content - but CuBe doesn't)
the 2.5% or lower Be content was/is the limit of the 'carcinogen rules'
outstandingly strong and hard as well as very high in thermal conductivity - so favoured for valve seats
especially with titanium valves as it's non-galling
mostly I used the hardest grades but machining was good
or unhardened for forming it was then easily hardened by low heat (age hardening)
hardened and cold-worked I could take it to c.10000 ppm of elastic strain - better than any steel
so it might allow bigger valves than would any other insert materials