<div dir="ltr">That's a very good question. I don't know about the MD specifically, but in very general terms, diesels get their increased fuel efficiency primarily from the high compression ratio, which means high combustion temperatures, which at least suggests that even older diesels used some kind of hard seat (induction hardened, or a hardened insert). <div><br></div><div>SO</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Dec 4, 2020 at 8:16 AM Bill Brueck <<a href="mailto:bill@apluscomputer.com">bill@apluscomputer.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal">How does this all relate to diesel engines? Was lead added to diesel fuel in those days, or were the engines (valve seats) designed to not need the lead?
<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thinking of my Farmall MD, which father in law bought new. It hasn’t seen enough hours for years to matter, I expect. When I joined the family in the late 60’s it was already largely retired. I remember running a rotary hoe with it once.<u></u><u></u></p>
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<p class="MsoNormal">B²<u></u><u></u></p>
<p class="MsoNormal">Bill Brueck<u></u><u></u></p>
<p class="MsoNormal"> Pine Island, MN USA<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal"><b>From:</b> AT <<a href="mailto:at-bounces@lists.antique-tractor.com" target="_blank">at-bounces@lists.antique-tractor.com</a>> <b>On Behalf Of
</b><a href="mailto:drgerber@bright.net" target="_blank">drgerber@bright.net</a><br>
<b>Sent:</b> Friday, December 4, 2020 6:56 AM<br>
<b>To:</b> 'Antique Tractor Email Discussion Group' <<a href="mailto:at@lists.antique-tractor.com" target="_blank">at@lists.antique-tractor.com</a>><br>
<b>Subject:</b> Re: [AT] [External] Re: Valve Seat Inserts<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><span style="font-size:14pt;font-family:"Calibri Light",sans-serif">The hardened seat installation was more needed for high RPM engines with high compression. That certainly does not apply to old 2 cylinder John Deere engines; low compression
in comparison, as well as low RPM made to run on cheap fuels. I have had to get the machine shop to put valve seats in two old Deeres; one was an LA which has a flat head and where the seats are in the block; it had been overhauled several times; countless
hours of abuse by a couple of previous owners; and the engine was so loose it would build up compression in the pan and blow the breather cap 50 feet in the air. It needed new valve seat inserts to make it run again. The other was an MT where the head was
pretty destroyed but salvageable. It had sentimental value as it was worn out when I purchased it many years ago. My father in law got scared once bush hogging with an old B with a hand clutch. I was overseas in the Army, and when I got back to the US I
bought the MT because it had a foot clutch and he was taking care of the farm and the fields in the soil conservation program had to be mowed. That poor thing bush hogged through material as tall as the tractor, and he literally wore it out. I restored it
last year, have way too much money in it, but it will stay in the family. <u></u>
<u></u></span></p>
<p class="MsoNormal"><span style="font-size:14pt;font-family:"Calibri Light",sans-serif"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:14pt;font-family:"Calibri Light",sans-serif">Dave Gerber
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<p class="MsoNormal"><span style="font-size:14pt;font-family:"Calibri Light",sans-serif">Ohio<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:14pt;font-family:"Calibri Light",sans-serif"><u></u> <u></u></span></p>
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<p class="MsoNormal"><b>From:</b> AT <<a href="mailto:at-bounces@lists.antique-tractor.com" target="_blank">at-bounces@lists.antique-tractor.com</a>>
<b>On Behalf Of </b>Jim Becker<br>
<b>Sent:</b> Thursday, December 3, 2020 11:36 PM<br>
<b>To:</b> Antique Tractor Email Discussion Group <<a href="mailto:at@lists.antique-tractor.com" target="_blank">at@lists.antique-tractor.com</a>><br>
<b>Subject:</b> Re: [AT] [External] Re: Valve Seat Inserts<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black">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!<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black"> <u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black">Was a waste of effort.<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black"> <u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black">Jim Becker<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:10pt;font-family:Tahoma,sans-serif;color:black"> <u></u><u></u></span></p>
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<p class="MsoNormal" style="background:whitesmoke"><b><span style="font-size:10pt;font-family:Tahoma,sans-serif;color:black">From:</span></b><span style="font-size:10pt;font-family:Tahoma,sans-serif;color:black"> Jason
<u></u><u></u></span></p>
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<p class="MsoNormal" style="background:whitesmoke"><b><span style="font-size:10pt;font-family:Tahoma,sans-serif;color:black">Sent:</span></b><span style="font-size:10pt;font-family:Tahoma,sans-serif;color:black"> Thursday, December 03, 2020 8:24 AM<u></u><u></u></span></p>
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<p class="MsoNormal" style="background:whitesmoke"><b><span style="font-size:10pt;font-family:Tahoma,sans-serif;color:black">To:</span></b><span style="font-size:10pt;font-family:Tahoma,sans-serif;color:black"> Antique Tractor Email Discussion Group
<u></u><u></u></span></p>
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<p class="MsoNormal" style="background:whitesmoke"><b><span style="font-size:10pt;font-family:Tahoma,sans-serif;color:black">Subject:</span></b><span style="font-size:10pt;font-family:Tahoma,sans-serif;color:black"> Re: [AT] [External] Re: Valve Seat
Inserts<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black"> <u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black">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.
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<p class="MsoNormal"><span style="font-size:12pt;color:black"> <u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black">Very old low compression motors often don't need this done because their combustion temperatures are so low.<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black"> <u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black">Jason<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black"> <u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black">On Thu, Dec 3, 2020, 8:08 AM Gunnells, Brad R <<a href="mailto:brad-gunnells@uiowa.edu" target="_blank">brad-gunnells@uiowa.edu</a>> wrote:<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12pt;color:black">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%20on%20behalf%20of%20deanvp@att.net" target="_blank">at-bounces@lists.antique-tractor.com on behalf of 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">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">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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