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Re: [TR] Advice on high compression head

To: DAVID MASSEY <dave1massey@cs.com>
Subject: Re: [TR] Advice on high compression head
From: Dave Connitt <dconnitt@fuse.net>
Date: Wed, 7 Apr 2021 18:22:58 -0400
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Hi Cliff,
A lot of racers have milled the heads of wet liner engines to increase compr=
ession. In Kas Kastner=E2=80=99s TR4/TR4A competition preparation manual, he=
 goes into much detail about how to reshape the combustion chambers in the h=
ead to reduce/eliminate =E2=80=9Chot spots=E2=80=9D. This may be the cause o=
f your pre-ignition. Yoy may want to get that book and read over his cylinde=
r head chapter. Regarding the push rod length, the length reduction is direc=
tly related to how much material is removed from the head so just buying sho=
rtened pushrods won=E2=80=99t get you the best results. I think you should f=
igure out how much material was removed from the =E2=80=9Cstock=E2=80=9D hea=
d and shorten the pushrods accordingly.=20
I think you can certainly save the head but you will need to do some homewor=
k reading over Kas=E2=80=99s competition prep manual and find a good automot=
ive machinist for the pushrods.
Dave Connitt=20

Sent from my iPhone

> On Apr 7, 2021, at 5:41 PM, DAVID MASSEY <dave1massey@cs.com> wrote:
>=20
> =EF=BB=BF
> I went the band-aid route on my TR3 for the same reason.  But the right wa=
y is to get a machinist to shorten the pushrods.  BPNW sells short rods for t=
he TR6/SC engine but at that time they didn't have any for the wet-sleeve en=
gine.
>=20
> Dave=20
>=20
>=20
>=20
> -----Original Message-----
> From: Cliff Hansen <cliff_hansen@outlook.com>
> To: list Triumph <triumphs@autox.team.net>
> Sent: Wed, Apr 7, 2021 4:23 pm
> Subject: [TR] Advice on high compression head
>=20
> The telenovela =E2=80=9CWhat=E2=80=99s going on with this 4A cylinder head=
=E2=80=9D has developed a new plot twist.
> =20
> The head, after cleanup, measures 3.21=E2=80=9D from bottom to the surface=
 for the valve cover gasket. Stock is 3.330 (if I got the number correctly).=
 Some PO cut 0.11 off, because only 0.010=E2=80=9D was removed in this round=
 of clean up. Now I can see an explanation for the persistent pinging I=E2=80=
=99ve dealt with over the last few years (head has been milled so compressio=
n is high, material near intake valves has been thinned, increasing likeliho=
od of hot spots =E2=80=93 I=E2=80=99m getting this from Kastner=E2=80=99s pr=
eparation book), which I had thought was due to leaking intakes, carb shafts=
, or operating at higher altitude.
> =20
> As is, I can=E2=80=99t use this head because there is not enough slack in t=
he valve train to give 0.010=E2=80=9D clearance on several valves. I didn=E2=
=80=99t notice before, but now that I am looking, all the valve adjusters we=
re nearly backed out all the way.
> =20
> Looking for advice from the list: is there any reasonable way to use this h=
ead?
> - I=E2=80=99d prefer to reduce compression but don=E2=80=99t see any reaso=
nable way to accomplish that. I called GasketWorks and he gently discouraged=
 me from getting a custom thick head gasket, saying instead I=E2=80=99d be b=
etter off finding a head which had not been milled so much.
>  - Shimming the rocker pedestals to get valve clearance feels like a banda=
id which certainly won=E2=80=99t address the pinging (assuming that the ping=
ing is a result of the shortened head).
> =20
> Would appreciate any advice on the way forward.
> =20
> Cliff
> =20
> Sent from Mail for Windows 10
> =20
> ** triumphs@autox.team.net **
>=20
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e
>=20
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ssey@cs.com
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>=20
> Donate: http://www.team.net/donate.html
> Archive: http://www.team.net/pipermail/triumphs  http://www.team.net/archi=
ve
>=20
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t@fuse.net

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto">Hi Cliff,<div>A lot of racers have milled t=
he heads of wet liner engines to increase compression. In Kas Kastner=E2=80=99=
s TR4/TR4A competition preparation manual, he goes into much detail about ho=
w to reshape the combustion chambers in the head to reduce/eliminate =E2=80=9C=
hot spots=E2=80=9D. This may be the cause of your pre-ignition. Yoy may want=
 to get that book and read over his cylinder head chapter. Regarding the pus=
h rod length, the length reduction is directly related to how much material i=
s removed from the head so just buying shortened pushrods won=E2=80=99t get y=
ou the best results. I think you should figure out how much material was rem=
oved from the =E2=80=9Cstock=E2=80=9D head and shorten the pushrods accordin=
gly.&nbsp;</div><div>I think you can certainly save the head but you will ne=
ed to do some homework reading over Kas=E2=80=99s competition prep manual an=
d find a good automotive machinist for the pushrods.</div><div>Dave Connitt&=
nbsp;<br><br><div dir=3D"ltr">Sent from my iPhone</div><div dir=3D"ltr"><br>=
<blockquote type=3D"cite">On Apr 7, 2021, at 5:41 PM, DAVID MASSEY &lt;dave1=
massey@cs.com&gt; wrote:<br><br></blockquote></div><blockquote type=3D"cite"=
><div dir=3D"ltr">=EF=BB=BF
<div style=3D"color:black;font: 12pt Arial, Helvetica, sans-serif;">
<div> <font size=3D"3">I went the band-aid route on my TR3 for the same reas=
on.&nbsp; But the right way is to get a machinist to shorten the pushrods.&n=
bsp; BPNW sells short rods for the TR6/SC engine but at that time they didn'=
t have any for the wet-sleeve engine.</font><br>
</div>

<div> <br>
</div>

<div style=3D"clear:both"><font size=3D"4">Dave </font><br>
<br>
</div>

<div> <br>
</div>

<div> <br>
</div>

<div style=3D"font-family:arial,helvetica;font-size:10pt;color:black"><font s=
ize=3D"2">-----Original Message-----<br>
From: Cliff Hansen &lt;cliff_hansen@outlook.com&gt;<br>
To: list Triumph &lt;triumphs@autox.team.net&gt;<br>
Sent: Wed, Apr 7, 2021 4:23 pm<br>
Subject: [TR] Advice on high compression head<br>
<br>

<div id=3D"yiv4309632913">

=20
=20
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<div>

<div class=3D"yiv4309632913WordSection1">

<div class=3D"yiv4309632913MsoNormal">The telenovela =E2=80=9CWhat=E2=80=99s=
 going on with this 4A cylinder head=E2=80=9D has developed a new plot twist=
.</div>


<div class=3D"yiv4309632913MsoNormal"> &nbsp;</div>
=20

<div class=3D"yiv4309632913MsoNormal">The head, after cleanup, measures 3.21=
=E2=80=9D from bottom to the surface for the valve cover gasket. Stock is 3.=
330 (if I got the number correctly). Some PO cut 0.11 off, because only 0.01=
0=E2=80=9D was removed in this round of clean up. Now I can see
 an explanation for the persistent pinging I=E2=80=99ve dealt with over the l=
ast few years (head has been milled so compression is high, material near in=
take valves has been thinned, increasing likelihood of hot spots =E2=80=93 I=
=E2=80=99m getting this from Kastner=E2=80=99s preparation book),
 which I had thought was due to leaking intakes, carb shafts, or operating a=
t higher altitude.</div>
=20

<div class=3D"yiv4309632913MsoNormal"> &nbsp;</div>
=20

<div class=3D"yiv4309632913MsoNormal">As is, I can=E2=80=99t use this head b=
ecause there is not enough slack in the valve train to give 0.010=E2=80=9D c=
learance on several valves. I didn=E2=80=99t notice before, but now that I a=
m looking, all the valve adjusters were nearly backed out all the way.</div>=



<div class=3D"yiv4309632913MsoNormal"> &nbsp;</div>
=20

<div class=3D"yiv4309632913MsoNormal">Looking for advice from the list: is t=
here any reasonable way to use this head?</div>


<div class=3D"yiv4309632913MsoNormal">- I=E2=80=99d prefer to reduce compres=
sion but don=E2=80=99t see any reasonable way to accomplish that. I called G=
asketWorks and he gently discouraged me from getting a custom thick head gas=
ket, saying instead I=E2=80=99d be better off finding a head which had
 not been milled so much. </div>


<div class=3D"yiv4309632913MsoNormal">&nbsp;- Shimming the rocker pedestals t=
o get valve clearance feels like a bandaid which certainly won=E2=80=99t add=
ress the pinging (assuming that the pinging is a result of the shortened hea=
d).</div>


<div class=3D"yiv4309632913MsoNormal"> &nbsp;</div>
=20

<div class=3D"yiv4309632913MsoNormal">Would appreciate any advice on the way=
 forward.</div>


<div class=3D"yiv4309632913MsoNormal"> &nbsp;</div>
=20

<div class=3D"yiv4309632913MsoNormal">Cliff</div>


<div class=3D"yiv4309632913MsoNormal"> &nbsp;</div>
=20

<div class=3D"yiv4309632913MsoNormal">Sent from <a rel=3D"nofollow noopener n=
oreferrer" target=3D"_blank" href=3D"https://go.microsoft.com/fwlink/?LinkId=
=3D550986">
Mail</a> for Windows 10</div>


<div class=3D"yiv4309632913MsoNormal"> &nbsp;</div>
=20
</div>

</div>


</div>
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