<VV> Valve Seat Fit

[levair at aol.com]

One exception would be to weld up the valve pockets before machining so that the much harder weld metal compared to cast will resist the heat cycles better. 
Gosh, I hope that there is at least two opinions worth listening to.
Warren 
 
-----Original Message-----
From: vairologist at verizon.net
To: virtualvairs at corvair.org
Sent: Thu, 3 May 2007 11:09 AM
Subject: <VV> Valve Seat Fit


Smitty Says:  since I am the only one with an opinion worth listening to, here 
is mine.  .006 or .007 under seat size is a good place to start but here is 
something that is largely ignored.  The surrounding aluminum only has so much 
"memory".  That is its ability to return to a cool state compression around the 
seat.  The more force encountered by it trying to shrink against the seat, the 
less it is capable of maintaining that force on the next heat cycle.  So if you 
have a seat fitted at .005 and another fitted at .010, within very few heat 
cycles they will both be exerting the same shrink force on the seat.  I don't 
know of anyone who has pulled a perfectly good fitting seat out to measure the 
seat bore after a hundred cycles just to measure it so this will just have to 
remain my opinion.
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