Dear Clive,
How interesting a post!
In Dover,New Jersey in the states here, is a shop called MANX CYCLE. Its
owner
and founder, Rich Lamm, drove the Manx on the Isle of Wight race and that
gave him the impetus to start his shop. I believe they are the foremost
British motorcycle restoration business on the East Coast. I've seen
such editions as Thruxton Velocettes, BSA's, Trumpets and Vincents
sitting in their driveways. A real museum, but also a working facility
with
most space devoted to pure machining operations.
In fact, the subject of sodium-filled poppet valves was closely discussed
when I visited. The low melting point of the sodium would make the
interior of the valve body conduct heat much faster from the valve faces,
but the problem of stem-distortion and a miserable Mean Time Between
failure
versus the cost made the re-issuance unfeasible.
If any of you are interested, MANX is on Route 46 in Dover.
Sorry for the off-shoot, but I couldn't resist replying to so great
a post.
Sincerely,
Hal
W4HBM
On Sun, 5 Sep 2004 21:29:48 +0100 (BST) =?iso-8859-1?q?CLIVE=20COLLINS?=
<dartaviation@btopenworld.com> writes:
> This may seem to be a bit way out for this field of engineering but
> there might be some mileage in considering the method.
> Norton Motorcycle company produced a very fast racing machine in the
> fifties and sixties (The Manxman 500) and had problems with the heat
> generated distorting the exhaust valve stems.
> Their answer after a lot of research was to make the exhaust valve
> stem hollow and fill it with Sodium with significantly good results.
> As I am not a metallurgist, I dont begin to undestand the theory,
> all I know is from experience, it worked. I wonder if a similar
> arrangement might be applied to the coil cooling discussion that is
> presently featuring on this reflector.
> Regards,
>
> Clive GW3WEQ
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