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If you want to save the head you may be able to lower the compression ratio
a bit by reshaping the combustion chamber. This is theoretically, I don't
know how much can be removed, Kastner book would be a starting point, but
you would probably want to take out more than that, measure combustion
chamber size, etc.
On Wed, Apr 7, 2021, 5:23 PM Dave Connitt <dconnitt@fuse.net> wrote:
> Hi Cliff,
> A lot of racers have milled the heads of wet liner engines to increase
> compression. In Kas Kastner=E2=80=99s TR4/TR4A competition preparation ma=
nual, he
> goes into much detail about how to reshape the combustion chambers in the
> head to reduce/eliminate =E2=80=9Chot spots=E2=80=9D. This may be the cau=
se of your
> pre-ignition. Yoy may want to get that book and read over his cylinder he=
ad
> chapter. Regarding the push rod length, the length reduction is directly
> related to how much material is removed from the head so just buying
> shortened pushrods won=E2=80=99t get you the best results. I think you sh=
ould
> figure out how much material was removed from the =E2=80=9Cstock=E2=80=9D=
head and shorten
> the pushrods accordingly.
> I think you can certainly save the head but you will need to do some
> homework reading over Kas=E2=80=99s competition prep manual and find a go=
od
> automotive machinist for the pushrods.
> Dave Connitt
>
> Sent from my iPhone
>
> On Apr 7, 2021, at 5:41 PM, DAVID MASSEY <dave1massey@cs.com> wrote:
>
> =EF=BB=BF
> I went the band-aid route on my TR3 for the same reason. But the right
> way is to get a machinist to shorten the pushrods. BPNW sells short rods
> for the TR6/SC engine but at that time they didn't have any for the
> wet-sleeve engine.
>
> Dave
>
>
>
> -----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
>
> The telenovela =E2=80=9CWhat=E2=80=99s going on with this 4A cylinder hea=
d=E2=80=9D has developed
> a new plot twist.
>
> The head, after cleanup, measures 3.21=E2=80=9D from bottom to the surfac=
e 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 cl=
ean up.
> Now I can see an explanation for the persistent pinging I=E2=80=99ve deal=
t with
> over the last few years (head has been milled so compression is high,
> material near intake valves has been thinned, increasing likelihood of ho=
t
> spots =E2=80=93 I=E2=80=99m getting this from Kastner=E2=80=99s preparati=
on book), which I had
> thought was due to leaking intakes, carb shafts, or operating at higher
> altitude.
>
> As is, I can=E2=80=99t use this head because there is not enough slack in=
the
> 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 were nearly
> backed out all the way.
>
> Looking for advice from the list: is there any reasonable way to use this
> head?
> - I=E2=80=99d prefer to reduce compression but don=E2=80=99t see any reas=
onable 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 better =
off
> finding a head which had not been milled so much.
> - Shimming the rocker pedestals to get valve clearance feels like a
> bandaid which certainly won=E2=80=99t address the pinging (assuming that =
the
> pinging is a result of the shortened head).
>
> Would appreciate any advice on the way forward.
>
> Cliff
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=3D550986> for
> Windows 10
>
> ** triumphs@autox.team.net **
>
> Donate: http://www.team.net/donate.html
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<div dir=3D"auto">If you want to save the head you may be able to lower the=
compression ratio a bit by reshaping the combustion chamber.=C2=A0 This is=
theoretically, I don't know how much can be removed, Kastner book woul=
d be a starting point, but you would probably want to take out more than th=
at, measure combustion chamber size, etc.</div><br><div class=3D"gmail_quot=
e"><div dir=3D"ltr" class=3D"gmail_attr">On Wed, Apr 7, 2021, 5:23 PM Dave =
Connitt <<a href=3D"mailto:dconnitt@fuse.net";>dconnitt@fuse.net</a>> =
wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8e=
x;border-left:1px #ccc solid;padding-left:1ex"><div dir=3D"auto">Hi Cliff,<=
div>A lot of racers have milled the heads of wet liner engines to increase =
compression. In Kas Kastner=E2=80=99s TR4/TR4A competition preparation manu=
al, he goes into much detail about how to reshape the combustion chambers i=
n the head to reduce/eliminate =E2=80=9Chot spots=E2=80=9D. This may be the=
cause of your pre-ignition. Yoy may want to get that book and read over hi=
s cylinder head chapter. Regarding the push rod length, the length reductio=
n is directly related to how much material is removed from the head so just=
buying shortened pushrods won=E2=80=99t get you the best results. I think =
you should figure out how much material was removed from the =E2=80=9Cstock=
=E2=80=9D head and shorten the pushrods accordingly.=C2=A0</div><div>I thin=
k you can certainly save the head but you will need to do some homework rea=
ding over Kas=E2=80=99s competition prep manual and find a good automotive =
machinist for the pushrods.</div><div>Dave Connitt=C2=A0<br><br><div dir=3D=
"ltr">Sent from my iPhone</div><div dir=3D"ltr"><br><blockquote type=3D"cit=
e">On Apr 7, 2021, at 5:41 PM, DAVID MASSEY <<a href=3D"mailto:dave1mass=
ey@cs.com" target=3D"_blank" rel=3D"noreferrer">dave1massey@cs.com</a>> =
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 rea=
son.=C2=A0 But the right way is to get a machinist to shorten the pushrods.=
=C2=A0 BPNW sells short rods for the TR6/SC engine but at that time they di=
dn'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=
size=3D"2">-----Original Message-----<br>
From: Cliff Hansen <<a href=3D"mailto:cliff_hansen@outlook.com"; target=
=3D"_blank" rel=3D"noreferrer">cliff_hansen@outlook.com</a>><br>
To: list Triumph <<a href=3D"mailto:triumphs@autox.team.net"; target=3D"_=
blank" rel=3D"noreferrer">triumphs@autox.team.net</a>><br>
Sent: Wed, Apr 7, 2021 4:23 pm<br>
Subject: [TR] Advice on high compression head<br>
<br>
<div id=3D"m_5256231747994726540yiv4309632913">
=20
=20
<div>
<div>
<div>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> =C2=A0</div>
=20
<div>The head, after cleanup, measures 3.21=E2=80=9D from bottom to the sur=
face for the valve cover gasket. Stock is 3.330 (if I got the number correc=
tly). 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 compression is high, material near=
intake 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 =
at higher altitude.</div>
=20
<div> =C2=A0</div>
=20
<div>As is, I can=E2=80=99t use this head because there is not enough slack=
in the valve train to give 0.010=E2=80=9D clearance on several valves. I d=
idn=E2=80=99t notice before, but now that I am looking, all the valve adjus=
ters were nearly backed out all the way.</div>
<div> =C2=A0</div>
=20
<div>Looking for advice from the list: is there any reasonable way to use t=
his head?</div>
<div>- I=E2=80=99d prefer to reduce compression but don=E2=80=99t see any r=
easonable way to accomplish that. I called GasketWorks and he gently discou=
raged me from getting a custom thick head gasket, saying instead I=E2=80=99=
d be better off finding a head which had
not been milled so much. </div>
<div>=C2=A0- Shimming the rocker pedestals to get valve clearance feels lik=
e a bandaid which certainly won=E2=80=99t address the pinging (assuming tha=
t the pinging is a result of the shortened head).</div>
<div> =C2=A0</div>
=20
<div>Would appreciate any advice on the way forward.</div>
<div> =C2=A0</div>
=20
<div>Cliff</div>
<div> =C2=A0</div>
=20
<div>Sent from <a rel=3D"nofollow noopener noreferrer noreferrer" href=3D"h=
ttps://go.microsoft.com/fwlink/?LinkId=3D550986" target=3D"_blank">
Mail</a> for Windows 10</div>
<div> =C2=A0</div>
=20
</div>
</div>
</div>
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