[xj-s] Valve Seat Deformation Theory

["David Johnson" <davidj@ecentral.com>]

Kirby I need to reply to these Emails on YIELDING of the metallic
components. I am a structures aerospace engineer, worked around the world
on F18's, Commercial airplanes (Airbus etc), Hovercraft, Satellites,
rockets etc. etc. I analyze aircraft wings and that sought of stuff.

Anyway, I am sorry to say it is IMPOSSIBLE to yield the valve seat or the
block due to the thermal stresses. The temperature difference will not
create sufficient strain (i.e. deformation). The issue here is that the
interference fit 0.002 to 0.006 is insufficient to cope with the
differential expansion between the two materials. Hence the valve guides
fall out at a high temp. It is late at night and too late to supply the
equations, but trust me you are incorrect in your yielding statement. If
you insist I will send details later.

Dave Johnson (Mr Brit in Denver)
Aerospace Structures Engineer
Two Hess Convertibles (His and Hers)


Something sounded oversimplified there.  Relative expansion between
Al and Fe over what temperature change?  And wouldn't this amount of
deformation need to be ADDED to the residual deformation from the
.002"-.006" interference fit to determine whether or not the TOTAL
deformation of the valve seat approaches the yield point?

- -- Kirbert      |     If anything is to be accomplished,
                 |     some rules must be broken.
                 |          - Palm's Postulate

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