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<DIV>As far as I could see, the whole hardened valve seat problem was a lot of
Chicken Little. Back when most of these old tractors (and old cars) were
made, regular gas had little to no lead in it anyway. Tractors in
particular were designed to run on the lowest octane gas commonly
available. Many just used valve seats ground straight into the cast iron
and ran for decades. The biggest exception was probably the LP heads that
came with hardened seats made for some engines. As leaded gas started
getting harder to find, machine shops all over the country were cutting out
perfectly good valve seats and sticking in replacement seats. Even if the
worst fears happened and there was excessive seat wear, the fix would still just
be to install valve seats. Worst case is the same as the preemptive
treatment!</DIV>
<DIV> </DIV>
<DIV>Was a waste of effort.</DIV>
<DIV> </DIV>
<DIV>Jim Becker</DIV>
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<DIV style="font-color: black"><B>From:</B> <A
title=dejoodster@gmail.com>Jason</A> </DIV>
<DIV><B>Sent:</B> Thursday, December 03, 2020 8:24 AM</DIV>
<DIV><B>To:</B> <A title=at@lists.antique-tractor.com>Antique Tractor Email
Discussion Group</A> </DIV>
<DIV><B>Subject:</B> Re: [AT] [External] Re: Valve Seat
Inserts</DIV></DIV></DIV>
<DIV> </DIV></DIV>
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<DIV>Yes. Lead in addition to be an antiknock agent also coated the valve seats
to prevent wear on valve seats. Only the exhaust seats need to be replaced.
<DIV> </DIV>
<DIV>Very old low compression motors often don't need this done because their
combustion temperatures are so low.</DIV>
<DIV> </DIV>
<DIV>Jason</DIV></DIV>
<DIV> </DIV>
<DIV class=gmail_quote>
<DIV class=gmail_attr dir=ltr>On Thu, Dec 3, 2020, 8:08 AM Gunnells, Brad R
<<A>brad-gunnells@uiowa.edu</A>> wrote:<BR></DIV>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex">Wasn't
there something also with the change from leaded to unleaded fuels? For some
reason I thought manufacturers started putting harder valve seats in later
model engines due to the limiting of lead. I could be way off here but I
thought I'd heard about that back in my dirt track racing
days.<BR><BR>Brad<BR><BR>On 12/3/20, 12:57 AM, "AT on behalf of Dean VP"
<<A rel=noreferrer target=_blank>at-bounces@lists.antique-tractor.com</A>
on behalf of <A rel=noreferrer target=_blank>deanvp@att.net</A>>
wrote:<BR><BR> Steve,<BR><BR> AHA,, I
completely overlooked they were two different parts. Now the
lights<BR> go on. Now I understand. The valve seat
might be damaged but the guide may<BR> still be good or vice
versa. As I recall that was more of a problem in
the<BR> 40's and 50's than it is
now.<BR><BR> Dean VP<BR> Apache Junction,
AZ<BR><BR> -----Original Message-----<BR>
From: AT <<A rel=noreferrer
target=_blank>at-bounces@lists.antique-tractor.com</A>> On Behalf Of Steve
W.<BR> Sent: Wednesday, December 2, 2020 11:38
PM<BR> To: Antique Tractor Email Discussion Group <<A
rel=noreferrer
target=_blank>at@lists.antique-tractor.com</A>><BR>
Subject: Re: [AT] Valve Seat Inserts<BR><BR> Dean VP
wrote:<BR> > Found a term in this company's price list
that rings some memories<BR> > but really hazy
ones. Could someone explain when and why
"Valve<BR> > Seat Inserts" are used rather than
replacing the whole valve guide?<BR> > Yes, they are a
little less expensive but not that much Please <BR>
> refresh my hazy memory from the 50's.<BR> >
<BR> > <BR> > <BR>
> Dean VP<BR> > <BR><BR> Different
parts. The valve guide holds the valve stem and keeps it
in<BR> position. The valve seat is the ground part of the
port in the head that the<BR> valve face seals against. The
reason for the inserts are a few, one is that<BR> you might
have a head with damaged or eroded seats and the valves
won't<BR> seal. You machine out the worn/damaged area, press
in the inserts and either<BR> peen the edge or more commonly
you bore the area for the seat with a step so<BR> the seat
locks into the head, to install you freeze the insert and heat
up<BR> the head. Then the two parts lock together as the
temperatures normalize.<BR> Have done both and prefer the
second option.<BR><BR> --<BR> Steve
W.<BR>
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