Subject: Re: [Fot] Head Thickness

From: Scott Janzen via Fot <[email-masked]>
Date: Fri, 10 Apr 2015 23:37:47 -0400

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I measured the two heads I have in use.
the 12:1 compression head measures 3.18" and the 11.5:1 head measures =
about 3.23.  Both heads are installed so perfect measurements are tough =
to get.  nonetheless, if your head was milled that much you would have =
numerous openings into the water passages.
Two solutions - find another head or two and test them before any work =
is done to see if you can find a better casting, or consider pop-up =
pistons.
I just checked piston to valve clearance on my new engine with modeling =
clay and there is certainly room to do this, though it may create other =
problems.  I'm running a cam with 0.554" of valve lift and there was =
easily 0.080" of clearance at the closest condition based on the =
modeling clay.

On Apr 10, 2015, at 9:07 PM, damys--- via Fot wrote:

So we just got the head back from the sonic test, picture attached.  Our =
numbers are quite a bit less than Chuck's.  Do you guys think we will be =
OK  at .065?  Our compression, according to our calculations, is 9.76:1. =
 This seems low to us.  Our combustion chambers are 34.5 cc's.  The =
total thickness of our head is 3.283, and we're bored .010 over.

Does the compression seem right for this thin of a head?  Are we OK with =
only .065" of material to the water jacket?

Thanks,

Dave and Alex
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<html><head></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">I =
measured the two heads I have in use.<div>the 12:1 compression head =
measures 3.18" and the 11.5:1 head measures about 3.23. &nbsp;Both heads =
are installed so perfect measurements are tough to get. =
&nbsp;nonetheless, if your head was milled that much you would have =
numerous openings into the water passages.</div><div>Two solutions - =
find another head or two and test them before any work is done to see if =
you can find a better casting, or consider pop-up pistons.</div><div>I =
just checked piston to valve clearance on my new engine with modeling =
clay and there is certainly room to do this, though it may create other =
problems. &nbsp;I'm running a cam with 0.554" of valve lift and there =
was easily 0.080" of clearance at the closest condition based on the =
modeling clay.</div><div><br></div><div><br></div><div><div><div>On Apr =
10, 2015, at 9:07 PM, damys--- via Fot wrote:</div><br =
class=3D"Apple-interchange-newline"><div align=3D"LEFT"><font =
face=3D"Verdana" size=3D"2" color=3D"#000000" letterspacing=3D"0" =
kerning=3D"0">So we just got the head back from the sonic test, picture =
attached.&nbsp; Our numbers are quite a bit less than Chuck's.&nbsp; Do =
you guys think we will be OK&nbsp; at .065?&nbsp; Our compression, =
according to our calculations, is 9.76:1.&nbsp; This seems low to =
us.&nbsp; Our combustion chambers are 34.5 cc's.&nbsp; The total =
thickness of our head is 3.283, and we're bored .010 =
over.</font></div><font face=3D"Verdana" size=3D"2" color=3D"#000000" =
letterspacing=3D"0" kerning=3D"0"><br></font><div align=3D"LEFT"><font =
face=3D"Verdana" size=3D"2" color=3D"#000000" letterspacing=3D"0" =
kerning=3D"0">Does the compression seem right for this thin of a =
head?&nbsp; Are we OK with only .065" of material to the water =
jacket?</font></div><font face=3D"Verdana" size=3D"2" color=3D"#000000" =
letterspacing=3D"0" kerning=3D"0"><br></font><div align=3D"LEFT"><font =
face=3D"Verdana" size=3D"2" color=3D"#000000" letterspacing=3D"0" =
kerning=3D"0">Thanks,</font></div><font face=3D"Verdana" size=3D"2" =
color=3D"#000000" letterspacing=3D"0" kerning=3D"0"><br></font><div =
align=3D"LEFT"><font face=3D"Verdana" size=3D"2" color=3D"#000000" =
letterspacing=3D"0" kerning=3D"0">Dave and =
Alex</font></div><span>&lt;IMAG1545.jpg&gt;</span>________________________=
_______________________<br><a =
href=3D"mailto:[email-masked]">[email-masked]</a><br><br>http://ww=
w.fot-racing.com<br><br>Donate: =
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http://autox.team.net/mailman/options/fot/[email-masked]<br><br><br></div>=
<br></div></body></html>=

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_______________________________________________
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---

From: Todd Redmond via Fot <[email-masked]>
Date: Sat, 11 Apr 2015 10:00:45 -0400 (EDT)

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Wait, we can add pictures to FoT?

Sorry, off topic.

On Fri, Apr 10, 2015 at 09:07 PM, damys--- via Fot wrote:

So we just got the head back from the sonic test, picture attached.=C2=A0 O=
ur=20
numbers are quite a bit less than Chuck's.=C2=A0 Do you guys think we will =
be=20
OK=C2=A0 at .065?=C2=A0 Our compression, according to our calculations, is=
=20
9.76:1.=C2=A0 This seems low to us.=C2=A0 Our combustion chambers are 34.5 =
cc's.=C2=A0=20
The total thickness of our head is 3.283, and we're bored .010 over.

Does the compression seem right for this thin of a head?=C2=A0 Are we OK wi=
th=20
only .065" of material to the water jacket?

Thanks,

Dave and Alex

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<div style=3D"font-family:Verdana">Wait, we can add pictures to FoT?</div><=
div style=3D"font-family:Verdana"><br></div><div style=3D"font-family:Verda=
na">Sorry, off topic.<br><br><br>On Fri, Apr 10, 2015 at 09:07 PM, damys---=
 via Fot wrote:<br><br><blockquote style=3D"border-left: 2px solid rgb(136,=
 136, 136); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex"><div align=3D"LEF=
T"><font face=3D"Verdana" size=3D"2" color=3D"#000000" letterspacing=3D"0" =
kerning=3D"0">So we just got the head back from the sonic test, picture att=
ached.&nbsp; Our numbers are quite a bit less than Chuck's.&nbsp; Do you gu=
ys think we will be OK&nbsp; at .065?&nbsp; Our compression, according to o=
ur calculations, is 9.76:1.&nbsp; This seems low to us.&nbsp; Our combustio=
n chambers are 34.5 cc's.&nbsp; The total thickness of our head is 3.283, a=
nd we're bored .010 over.</font></div><font face=3D"Verdana" size=3D"2" col=
or=3D"#000000" letterspacing=3D"0" kerning=3D"0"><br></font><div align=3D"L=
EFT"><font face=3D"Verdana" size=3D"2" color=3D"#000000" letterspacing=3D"0=
" kerning=3D"0">Does the compression seem right for this thin of a head?&nb=
sp; Are we OK with only .065" of material to the water jacket?</font></div>=
<font face=3D"Verdana" size=3D"2" color=3D"#000000" letterspacing=3D"0" ker=
ning=3D"0"><br></font><div align=3D"LEFT"><font face=3D"Verdana" size=3D"2"=
 color=3D"#000000" letterspacing=3D"0" kerning=3D"0">Thanks,</font></div><f=
ont face=3D"Verdana" size=3D"2" color=3D"#000000" letterspacing=3D"0" kerni=
ng=3D"0"><br></font><div align=3D"LEFT"><font face=3D"Verdana" size=3D"2" c=
olor=3D"#000000" letterspacing=3D"0" kerning=3D"0">Dave and Alex</font></di=
v><hr>_______________________________________________<br>
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