[Fot] Harden Valve Seats

[Joe Boruch]

Bill, I have only been doing them on the exhaust, since that is for the most
part where any valve recession should occur.  I have noticed, however, that
when I do not run air cleaners I have some intake valve recession.  I think
another challenge on the intake side to to get it to blend well enough not to
interfere with intake flow.  Joe(B)

-- WEmery7451 at aol.com wrote:
Dear FOT,

Whenever my machinist has set up a TR-3/4 engine head for me, he
automatically puts in harden valve seats for both the intake and exhaust
valves
.  I gave
one of my engine heads to Dan Styduhar, who has been helping me with the
TR-3.
His machinist highly recommends not to put the harden valve seats in for the
intake valve.  A lot of material is ground out the cast iron head to install
the valve seats, and there is not a lot of material between the intake and
exhaust valves to begin with.

My initial guesses would be:

-There are two different materials involved -- cast iron and steel.  Maybe
the steel valve seats would not count as material being replaced, and that
the
cast iron could crack under the seats.

-If there is not a great deal of exhaust gasses blowing past the closed
intake valves, the intake valves would not need the harden seats -- keeping
in
mind
that there is a tremendous pressure surge during the combustion stroke.

Does anyone have any thought on this subject?

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