Subject: [Fot] valve seat crack?

From: Brian Dennis <[email-masked]>
Date: Fri, 19 Feb 2016 20:50:47 +0000 (UTC)

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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 referenc=
ed the iron head stock car racers that do it all the time. This is on two G=
T6 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 t=
rying to get 100K miles on a road going car but for racing not to worry abo=
ut it. Check it anytime the head is off. the cracks are in line with a cast=
ing line in the valve pocket/port.=C2=A0
Thoughts on that?
=C2=A0I also have an "A" cast head that is not cracked. The B head is suppo=
sedly better. I know this came up a couple of months ago but I don't rememb=
er the differences between the A head and =C2=A0the B head.
Thanks, BrianFoster, RI

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sans-serif;font-size:16px"><div id=3D"yui_3_16_0_1_1455913856463_3874" dir=
=3D"ltr">I have been told by 2 different machine shops that a hairline crac=
k 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 h=
ear 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 als=
o does a lot of drag race motors. Both also noted that it is questionable i=
f 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 wi=
th a casting line in the valve pocket/port.&nbsp;</div><div id=3D"yui_3_16_=
0_1_1455913856463_3874" dir=3D"ltr"><br></div><div id=3D"yui_3_16_0_1_14559=
13856463_3874" dir=3D"ltr">Thoughts on that?</div><div id=3D"yui_3_16_0_1_1=
455913856463_3874" dir=3D"ltr"><br></div><div id=3D"yui_3_16_0_1_1455913856=
463_3874" dir=3D"ltr">&nbsp;I also have an "A" cast head that is not cracke=
d. 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 &nbsp;the B=
 head.</div><div id=3D"yui_3_16_0_1_1455913856463_3874" dir=3D"ltr"><br></d=
iv><div id=3D"yui_3_16_0_1_1455913856463_3874" dir=3D"ltr">Thanks, Brian</d=
iv><div id=3D"yui_3_16_0_1_1455913856463_3874" dir=3D"ltr">Foster, RI</div>=
<div id=3D"yui_3_16_0_1_1455913856463_3874" dir=3D"ltr"><br></div></div></b=
ody></html>
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_______________________________________________
[email-masked]

http://www.fot-racing.com

Archive: http://www.team.net/archive

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From: "Steve Yott" <[email-masked]>
Date: Fri, 19 Feb 2016 15:16:15 -0600

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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.

=20

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!

=20

Steve Yott

=20

From: Fot [mailto:[email-masked]] On Behalf Of Brian Dennis
Sent: Friday, February 19, 2016 2:51 PM
To: FOT List
Subject: [Fot] valve seat crack?

=20

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.=20

=20

Thoughts on that?

=20

 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.

=20

Thanks, Brian

Foster, RI

=20

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<p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I believe I have answered a similar question =
previously.=C2=A0 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=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p>&nbsp;</o:p></span></p>

<p class=3DMsoNormal><span =
style=3D'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.=C2=A0 Most shops will first counter bore the =
intake seat
area and fit a new intake seat.=C2=A0 Once this is done they will then =
counter bore
the exhaust seat area and overlap into the new intake seat by just a =
little.=C2=A0
The new hardened exhaust seat is then installed and a normal machining =
of the
seats is accomplished.=C2=A0 =C2=A0I 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=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p>&nbsp;</o:p></span></p>

<p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Steve Yott<o:p></o:p></span></p>

<p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p>&nbsp;</o:p></span></p>

<div>

<div style=3D'border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt =
0in 0in 0in'>

<p class=3DMsoNormal><b><span =
style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span>=
</b><span
style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Fot
[mailto:[email-masked]] <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>

</div>

</div>

<p class=3DMsoNormal><o:p>&nbsp;</o:p></p>

<div>

<div id=3D"yui_3_16_0_1_1455913856463_3874">

<p class=3DMsoNormal style=3D'background:white'><span =
style=3D'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.&nbsp;<o:p></o:p></span></p>

</div>

<div id=3D"yui_3_16_0_1_1455913856463_3874">

<p class=3DMsoNormal style=3D'background:white'><span =
style=3D'font-family:"Helvetica","sans-serif";
color:black'><o:p>&nbsp;</o:p></span></p>

</div>

<div id=3D"yui_3_16_0_1_1455913856463_3874">

<p class=3DMsoNormal style=3D'background:white'><span =
style=3D'font-family:"Helvetica","sans-serif";
color:black'>Thoughts on that?<o:p></o:p></span></p>

</div>

<div id=3D"yui_3_16_0_1_1455913856463_3874">

<p class=3DMsoNormal style=3D'background:white'><span =
style=3D'font-family:"Helvetica","sans-serif";
color:black'><o:p>&nbsp;</o:p></span></p>

</div>

<div id=3D"yui_3_16_0_1_1455913856463_3874">

<p class=3DMsoNormal style=3D'background:white'><span =
style=3D'font-family:"Helvetica","sans-serif";
color:black'>&nbsp;I also have an &quot;A&quot; 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 &nbsp;the B =
head.<o:p></o:p></span></p>

</div>

<div id=3D"yui_3_16_0_1_1455913856463_3874">

<p class=3DMsoNormal style=3D'background:white'><span =
style=3D'font-family:"Helvetica","sans-serif";
color:black'><o:p>&nbsp;</o:p></span></p>

</div>

<div id=3D"yui_3_16_0_1_1455913856463_3874">

<p class=3DMsoNormal style=3D'background:white'><span =
style=3D'font-family:"Helvetica","sans-serif";
color:black'>Thanks, Brian<o:p></o:p></span></p>

</div>

<div id=3D"yui_3_16_0_1_1455913856463_3874">

<p class=3DMsoNormal style=3D'background:white'><span =
style=3D'font-family:"Helvetica","sans-serif";
color:black'>Foster, RI<o:p></o:p></span></p>

</div>

<div id=3D"yui_3_16_0_1_1455913856463_3874">

<p class=3DMsoNormal style=3D'background:white'><span =
style=3D'font-family:"Helvetica","sans-serif";
color:black'><o:p>&nbsp;</o:p></span></p>

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