On Wed, 20 Aug 2008 15:39:43 -0700 (PDT), wrote:



plastic probably would work if you lined the valve seat with soft
silicone.

I like it, rather than looking for rubber 'valve' .. ;-)

However I'm not sure how easy it will be to re-engineer in practice as
the seat is at the bottom of a fairly deep body.

Something else to think about though if the rubber won't recover
chemically (I've tried lighter fluid so far (no change), now on white
spirit).

All the best ..

T i m