<VV> Valve seats

[James Davis]

Having had the valve seats come loose on six 140 heads (two exhaust and 
four intakes), two 95 hp heads (two intakes) and three 110 heads (two 
intakes and one exhaust),  I guess I am loosing all the valve seats that 
Lon isn't.  Admittedly most of the seats came out in the 70s and 80s 
when the better machine shops didn't know Corvairs.  Only one valve seat 
is the last 20 years  (#2 intake in the UltraVan).  The good news I have 
never lost a seat in a head done by Ray Sedman or Micheal LeVeque.  That 
is in 47 years of only driving Corvair powered vehicles for over 500,000 
miles.
Jim Davis

On 5/3/2012 1:25 PM, Bryan Blackwell wrote:
> Thanks, that's quite helpful.  Follow up question - how do I figure out if the seats have been ground too many times?
>
> In all honesty, I'll probably still get new seats in heads I have done for a new engine.  They are in tight and have the minimum number of valve jobs - 1.
>
> --Bryan
>
> On May 3, 2012, at 1:14 PM, Mark Durham wrote:
>
>> I concur with Lon, if there is no pushed metal at the seat to head
>> interface in the ports or combustion chamber, REGARDLESS of history or
>> no history, they are OK to use as long as they have not been ground too
>> many times! I've done thousands of seats in automotive and aircraft,
>> and seats that begin to come loose at temp will move and push the
>> softer aluminum. if unsure, take some pics and send them. Mark Durham