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Brian,
This is actually a common issue and in about 85% of the cases can be
repaired by a decent machine shop. The dependency is how deep the crack =
is
in the head. The normal way to repair this is to mill out the intake =
valve
seat in the cast head in order to install a valve seat insert. The =
normal
replacement seats are in the area of =BC=94 deep and if the milling of =
the seat
pocket removes all of the crack then the insert is installed. A new =
exhaust
valve seat insert is then installed by milling the pocket in the head =
and
overlapping the new intake seat by a little bit.
=20
Bring the head to a competent shop and at worse all they will need to do =
is
set it up and mill the intake pocket to see how deep the crack is =
extended.
At this point they will fix it or deem it unusable.
=20
Steve Yott
=20
=20
From: Fot [mailto:fot-bounces@autox.team.net] On Behalf Of Brian
Sent: Sunday, January 03, 2016 10:05 AM
To: FOT <fot@autox.team.net>
Subject: [Fot] Valve seat crack
=20
I have a GT6 head with a cracked valve seat between the intake and =
exhaust
seats. Would it be worthwhile to magnaflux to determine how deep it goes
into the port then pending the depth install new seats. This is on an =
older
race head that is already ported. I do my own porting and last time took =
me
about 80 hours to do. So since I live in the real world with a regular =
day
job I am exploring options including time and money. If i can repair =
this
head at a reasonable cost then I would only need to clean up the port =
work
to match my current engine specs. Any input appreciated.
Thanks,=20
Brian
Foster, RI
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link=3D"#0563C1" vlink=3D"#954F72"><div class=3DWordSection1><p =
class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'=
>Brian,<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'=
>This is actually a common issue and in about 85% of the cases can be =
repaired by a decent machine shop.=A0 The dependency is how deep the =
crack is in the head.=A0 The normal way to repair this is to mill out =
the intake valve seat in the cast head in order to install a valve seat =
insert.=A0 The normal replacement seats are in the area of =BC” =
deep and if the milling of the seat pocket removes all of the crack then =
the insert is installed.=A0 A new exhaust valve seat insert is then =
installed by milling the pocket in the head and overlapping the new =
intake seat by a little bit.<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'=
>Bring the head to a competent shop and at worse all they will need to =
do is set it up and mill the intake pocket to see how deep the crack is =
extended.=A0 At this point they will fix it or deem it =
unusable.<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><p class=3DMsoNormal><span =
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0in 0in'><p class=3DMsoNormal><b><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span><=
/b><span style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'> =
Fot [mailto:fot-bounces@autox.team.net] <b>On Behalf Of =
</b>Brian<br><b>Sent:</b> Sunday, January 03, 2016 10:05 =
AM<br><b>To:</b> FOT <fot@autox.team.net><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><p =
class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'>I have a GT6 =
head with a cracked valve seat between the intake and exhaust seats. =
Would it be worthwhile to magnaflux to determine how deep it goes into =
the port then pending the depth install new seats. This is on an older =
race head that is already ported. I do my own porting and last time took =
me about 80 hours to do. So since I live in the real world with a =
regular day job I am exploring options including time and money. If i =
can repair this head at a reasonable cost then I would only need to =
clean up the port work to match my current engine specs. Any input =
appreciated.<br>Thanks, <br>Brian<br>Foster, =
RI<o:p></o:p></span></p></div></div></div></body></html>
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_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://www.team.net/archive
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