<div dir="auto">When I rebuilt the head on my Farmall H back in the late 90's it was recommended to use the new harder valve seats and the machine shop did put them in. Unleaded fuel was the reason for the old tractors to use those unless you always put additives with the gas.<div dir="auto">Dave Maynard</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Dec 3, 2020, 9:08 AM Gunnells, Brad R <<a href="mailto:brad-gunnells@uiowa.edu">brad-gunnells@uiowa.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">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 href="mailto:at-bounces@lists.antique-tractor.com" target="_blank" rel="noreferrer">at-bounces@lists.antique-tractor.com</a> on behalf of <a href="mailto:deanvp@att.net" target="_blank" rel="noreferrer">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 href="mailto:at-bounces@lists.antique-tractor.com" target="_blank" rel="noreferrer">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 href="mailto:at@lists.antique-tractor.com" target="_blank" rel="noreferrer">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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