<VV> Seat Life WAS Valve Seats

[Harry Yarnell]

One of the reasons 140's drop seats is they're bigger. Expansion rate of
aluminum is greater than steel, hence they have a greater chance of falling
out.



-----Original Message-----
From: virtualvairs-bounces at corvair.org
[mailto:virtualvairs-bounces at corvair.org] On Behalf Of Ken Pepke
Sent: Saturday, May 05, 2012 9:21 AM
To: Vair Views
Subject: <VV> Seat Life WAS Valve Seats


Lon's thinking is still correct.  Inserted valve seat failure is neither an
age nor a mileage condition.  A newly inserted valve seat starts its life
from exactly the same place as an original that has not moved.  That is to
say the newly installed seat has the same odds of failure as the unmoved
original which it replaced.  Seat failure comes with excessive heat [or poor
installation of a replacement.]   If a seat is replaced, it really needs to
be of the higher press variety because removal of the original seat damages
the head in the seat area.

Heads on a 140hp engine run hotter because they make more power, use more
fuel while doing so, and produce more heat, so they have a greater chance of
seat failure.  This frequently [but not always] happens on vacation such as
a long trip to a Corvair meet.  These are times when the car is loaded,
running faster than usual for prolonged periods of time and getting hotter
than usual.
  
Bottom line:  The single most important factor in longevity of replacement
valve seat inserts is the skill of the machinist.  

Ken P
Wyandotte, MI
Worry looks around; Sorry looks back, Faith looks up.

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