<VV> valve seats revisited (Engine Braking)

[Robert Henry]

When I dropped a seat in my Corvair it was on a trip to the store. Drove the car 
to the store, circulated around looking for a place to park, parked and went in 
the store. When I came out and started up it was making this noise. So much for 
the theory of a smoking hot engine at the climax of a hill climb. In fact, this 
engine seems to enjoy that kind of thing.

The valve seat failure occurred shortly after I'd rebuilt the engine. I'd seen 
no evidence of problems during the rebuild (well, except for the worn-out engine 
parts.) However, there was evidence and reports of overheating incidents in the 
engine's history before I got it. Broken fan belts, seized alternator, clogged 
air passages, broken heater hoses, etc. It may not be a single event but a 
history of overheating that causes the problem. Now it runs fairly cool.

Robert Henry
'65 Corsa Convertible Turbo
Knoxville, TN



________________________________
From: "RoboMan91324 at aol.com" <RoboMan91324 at aol.com>
To: virtualvairs at corvair.org; judynrandy at comcast.net
Sent: Tue, May 8, 2012 8:26:54 AM
Subject: <VV> valve seats revisited (Engine Braking)
...
Last, this has nothing to do with your post, Randy, but the  cooling 
(quenching) effect going from full power directly to downhill engine  braking 
being a major contributor to dropping a valve seat is questionable in my  
opinion.  I think the worst case situation for quenching would be running  full 
throttle (full load) uphill with resulting overheated heads and then  cresting 
the hill and running full throttle down the other side.  Full  engine 
braking has little to do with the dropped valve seats but going from full  load 
driving to low or normal load driving would be more dangerous because there  
is actual air flow quenching going on.  Of course, overheating the heads in  
and of itself is the root cause.

Doc