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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I believe I have answered a similar question previously. This
is a very common problem with cast iron heads and extremely common on Tractor
motor heads with cylinder #4 because of excessive heat buildup.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The fix is generally easy and the longevity of the fix is dependent
on the depth of the crack. Most shops will first counter bore the intake seat
area and fit a new intake seat. Once this is done they will then counter bore
the exhaust seat area and overlap into the new intake seat by just a little.
The new hardened exhaust seat is then installed and a normal machining of the
seats is accomplished. I have done a number of street engines in this manner
and the results are normally very good!<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Steve Yott<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Fot
[mailto:fot-bounces@autox.team.net] <b>On Behalf Of </b>Brian Dennis<br>
<b>Sent:</b> Friday, February 19, 2016 2:51 PM<br>
<b>To:</b> FOT List<br>
<b>Subject:</b> [Fot] valve seat crack?<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<div id="yui_3_16_0_1_1455913856463_3874">
<p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";
color:black'>I have been told by 2 different machine shops that a hairline
crack in the valve seat between intake and exhaust is not a big deal. They both
referenced the iron head stock car racers that do it all the time. This is on
two GT6 circle B heads I had magnafluxed. I was a little surprised to hear that
and just as surprised to hear the same from a second machine shop. Both of
these shops do a lot of work on circle track stuff. One I know also does a lot
of drag race motors. Both also noted that it is questionable if I was trying to
get 100K miles on a road going car but for racing not to worry about it. Check
it anytime the head is off. the cracks are in line with a casting line in the
valve pocket/port. <o:p></o:p></span></p>
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<p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";
color:black'><o:p> </o:p></span></p>
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<p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";
color:black'>Thoughts on that?<o:p></o:p></span></p>
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<p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";
color:black'><o:p> </o:p></span></p>
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<div id="yui_3_16_0_1_1455913856463_3874">
<p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";
color:black'> I also have an "A" cast head that is not cracked.
The B head is supposedly better. I know this came up a couple of months ago but
I don't remember the differences between the A head and the B head.<o:p></o:p></span></p>
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<p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";
color:black'><o:p> </o:p></span></p>
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<div id="yui_3_16_0_1_1455913856463_3874">
<p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";
color:black'>Thanks, Brian<o:p></o:p></span></p>
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<div id="yui_3_16_0_1_1455913856463_3874">
<p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";
color:black'>Foster, RI<o:p></o:p></span></p>
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<p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";
color:black'><o:p> </o:p></span></p>
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