Robert:
I had never heard this one either, so I am going to chalk it up
to urban legend.
I can say that my '74 with 69,000 miles had no valve seat
recession when I purchased it in 2003. I personally am of the mind that
a well tuned engine has minimal valve seat recession risk, even without
hardened seats.
I should also mention that Detroit NEVER used hardened inserts
even for unleaded fuel. Instead, they INDUCTION HARDENED the seats. This
involves using a water cooled electromagnet shaped to fit in the center
of the valve seat, and pumping loads of alternating current through the
magnet at a few kilohertz. This induces an "eddy current" in the valve
seat, which in a couple of seconds heats to its eutectic temperature
(iron blocks have trace amounts of carbon and nickel as I recall). The
carbon/nickel goes into solution in the iron (casting iron results in
most of the carbon being at grain boundaries in the metal) and then the
valve seat is quenched with water.
This results in the valve seat being very hard, while the rest
of the head is much more ductile. The hardened valve seat is contiguous
with the rest of the head, and can only be identified by inspection
under a microscope.
So, if Triumph EVER used hardened valve seats, they would not
have used inserts - too expensive and they can fall out (although this
is extremely unlikely). Induction hardening is faster, cheaper, and
stronger since the head and seat are one piece.
Vance
Vance Navarrette
Cogito Ergo Zoom
I think, therefore I go fast
-----Original Message-----
From: 6pack-bounces+vance.navarrette=intel.com@autox.team.net
[mailto:6pack-bounces+vance.navarrette=intel.com@autox.team.net] On
Behalf Of Robert Lang
Sent: Friday, May 09, 2008 12:54 PM
To: John VanNorman
Cc: 6-Pack
Subject: Re: [6pack] unleaded fuel
On Fri, 9 May 2008, John VanNorman wrote:
> I just noticed this thread on the 6-Pack website. I'll be honest, I
> never knew this:
>
>
http://www.6-pack.org/modules.php?name=Forums&file=viewtopic&p=37566#375
66
Me niether.
That's because I don't believe that it's accurate that Triumph
"switched"
to hardened valve seats.
<snip>
I have heads from all years and I have yet to find a hardened seat in a
factory head unless it was installed after the car was in service.
> John V.
> 1974 1/2 TR6
regards,
rml
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