This is a multipart message in MIME format.
--===============0458350360505244124==
boundary="----=_NextPart_000_00B1_01D16B28.79BC6A30"
Content-Language: en-us
This is a multipart message in MIME format.
------=_NextPart_000_00B1_01D16B28.79BC6A30
charset="utf-8"
Content-Transfer-Encoding: quoted-printable
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:fot-bounces@autox.team.net] 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
------=_NextPart_000_00B1_01D16B28.79BC6A30
charset="utf-8"
Content-Transfer-Encoding: quoted-printable
<html xmlns:v=3D"urn:schemas-microsoft-com:vml" =
xmlns:o=3D"urn:schemas-microsoft-com:office:office" =
xmlns:w=3D"urn:schemas-microsoft-com:office:word" =
xmlns:m=3D"http://schemas.microsoft.com/office/2004/12/omml"; =
xmlns=3D"http://www.w3.org/TR/REC-html40";>
<head>
<meta http-equiv=3DContent-Type content=3D"text/html; charset=3Dutf-8">
<meta name=3DGenerator content=3D"Microsoft Word 12 (filtered medium)">
<style>
<!--
/* Font Definitions */
@font-face
{font-family:Helvetica;
panose-1:2 11 6 4 2 2 2 2 2 4;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.Section1
{page:Section1;}
-->
</style>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext=3D"edit" spidmax=3D"1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext=3D"edit">
<o:idmap v:ext=3D"edit" data=3D"1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang=3DEN-US link=3Dblue vlink=3Dpurple>
<div class=3DSection1>
<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> </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> </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> </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: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>
</div>
</div>
<p class=3DMsoNormal><o:p> </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. <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> </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> </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'> 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>
</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> </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> </o:p></span></p>
</div>
</div>
</div>
</body>
</html>
------=_NextPart_000_00B1_01D16B28.79BC6A30--
--===============0458350360505244124==
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://www.team.net/archive
--===============0458350360505244124==--
|