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Cliff
Here is my experience with a milled TR4A head. After a couple of =
millings of the head I ended up somewhere around .110 off the head. I =
had 2 Head Gasket failures one caused by me using the wrong =93modern=94 =
head gasket from Cometic and the second because I failed to re-torque =
the head using an original Payen AE 330 head gasket. However I never had =
pinging issues using the current 93 octane premium fuel. The key here is =
to limit the amount of total timing advance to match the available fuel. =
I have a friend who had a similar amount milled from his head and =
didn=92t have any head gasket issues with the Cometic modern gasket. He =
drove his car much more aggressively than me as well. Can=92t explain =
why.
It=92s also very important that whichever gasket you use, the gasket =
does not protrude into the combustion chamber. It turned out the =
Cometic I used did and that=92s where it failed.
>From previous email with you I learned you are using the copper =
reproduction Payen 330 head gasket with 86mm liners. In my case I had =
87mm liners. That should work but be certain to re-torque the head after =
a few heat cycles. (I=92ve done that now with the latest install and so =
far all is good) I must also say I have replaced the .110 head with one =
milled only .075 and don=92t really notice much power loss over the .110 =
head. It=92s noted that the Kastner Comp manual only recommends .090 for =
a street engine. I changed heads because most summers I, along with =
several friends take long trips covering several thousand miles and I =
didn=92t want a head gasket failure miles from home. However; I do carry =
a spare head gasket and the tools to change it with me. Good insurance =
as no failures now after close to 6000 miles. Previous to me messing =
with that original milled head at .090 I drove the car for 30+ years and =
many thousands of miles without a failure using a Payen AE330 head =
gasket.
You can make that head work but retard the timing (I run 28 degrees =
total advance) you may need to back it off to less than 28 degrees. =
Re-torque the head more than once.
As for the push rod / valve adjustment issue. Call Ted at TSI and have =
him make a set of pushrods shortened by the amount removed from the head =
and you=92ll have your adjustment issues solved.
Hope this helps.
JVV
From: Cliff Hansen=20
Sent: Wednesday, April 7, 2021 5:23 PM
To: list Triumph=20
Subject: [TR] Advice on high compression head
The telenovela =93What=92s going on with this 4A cylinder head=94 has =
developed a new plot twist.
=20
The head, after cleanup, measures 3.21=94 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=94 was removed in this round of =
clean up. Now I can see an explanation for the persistent pinging I=92ve =
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 =96 I=92m getting this from Kastner=92s =
preparation book), which I had thought was due to leaking intakes, carb =
shafts, or operating at higher altitude.
=20
As is, I can=92t use this head because there is not enough slack in the =
valve train to give 0.010=94 clearance on several valves. I didn=92t =
notice before, but now that I am looking, all the valve adjusters were =
nearly backed out all the way.
=20
Looking for advice from the list: is there any reasonable way to use =
this head?
- I=92d prefer to reduce compression but don=92t see any reasonable way =
to accomplish that. I called GasketWorks and he gently discouraged me =
from getting a custom thick head gasket, saying instead I=92d be better =
off finding a head which had not been milled so much.=20
- Shimming the rocker pedestals to get valve clearance feels like a =
bandaid which certainly won=92t address the pinging (assuming that the =
pinging 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
-------------------------------------------------------------------------=
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** triumphs@autox.team.net **
Archive: http://www.team.net/pipermail/triumphs =
http://autox.team.net/mailman/options/triumphs/jerryvv@roadrunner.com
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<DIV dir=3Dltr>
<DIV style=3D"FONT-SIZE: 12pt; FONT-FAMILY: 'Calibri'; COLOR: #000000">
<DIV>Cliff</DIV>
<DIV> </DIV>
<DIV>Here is my experience with a milled TR4A head. After a couple of =
millings=20
of the head I ended up somewhere around .110 off the head. I had 2 Head =
Gasket=20
failures one caused by me using the wrong =93modern=94 head gasket from =
Cometic and=20
the second because I failed to re-torque the head using an original =
Payen AE 330=20
head gasket. However I never had pinging issues using the current 93 =
octane=20
premium fuel. The key here is to limit the amount of total timing =
advance to=20
match the available fuel. I have a friend who had a similar amount =
milled from=20
his head and didn=92t have any head gasket issues with the Cometic =
modern gasket.=20
He drove his car much more aggressively than me as well. Can=92t explain =
why.</DIV>
<DIV>It=92s also very important that whichever gasket you use, the =
gasket does not=20
protrude into the combustion chamber. It turned out the Cometic I =
used did=20
and that=92s where it failed.</DIV>
<DIV> </DIV>
<DIV>From previous email with you I learned you are using the copper=20
reproduction Payen 330 head gasket with 86mm liners. In my case I had =
87mm=20
liners. That should work but be certain to re-torque the head after a =
few heat=20
cycles. (I=92ve done that now with the latest install and so far all is =
good) I=20
must also say I have replaced the .110 head with one milled only .075 =
and don=92t=20
really notice much power loss over the .110 head. It=92s noted that the =
Kastner=20
Comp manual only recommends .090 for a street engine. I changed heads =
because=20
most summers I, along with several friends take long trips covering =
several=20
thousand miles and I didn=92t want a head gasket failure miles from =
home. However;=20
I do carry a spare head gasket and the tools to change it with me. Good=20
insurance as no failures now after close to 6000 miles. Previous to me =
messing=20
with that original milled head at .090 I drove the car for 30+ years and =
many=20
thousands of miles without a failure using a Payen AE330 head =
gasket.</DIV>
<DIV> </DIV>
<DIV>You can make that head work but retard the timing (I run 28 degrees =
total=20
advance) you may need to back it off to less than 28 degrees. Re-torque =
the head=20
more than once.</DIV>
<DIV> </DIV>
<DIV>As for the push rod / valve adjustment issue. Call Ted at TSI and =
have him=20
make a set of pushrods shortened by the amount removed from the head and =
you=92ll=20
have your adjustment issues solved.</DIV>
<DIV> </DIV>
<DIV>Hope this helps.</DIV>
<DIV> </DIV>
<DIV>JVV</DIV>
<DIV=20
style=3D'FONT-SIZE: small; TEXT-DECORATION: none; FONT-FAMILY: =
"Calibri"; FONT-WEIGHT: normal; COLOR: #000000; FONT-STYLE: normal; =
DISPLAY: inline'>
<DIV style=3D"FONT: 10pt tahoma">
<DIV><FONT size=3D3 face=3DCalibri></FONT> </DIV>
<DIV style=3D"BACKGROUND: #f5f5f5">
<DIV style=3D"font-color: black"><B>From:</B> <A=20
title=3Dcliff_hansen@outlook.com>Cliff Hansen</A> </DIV>
<DIV><B>Sent:</B> Wednesday, April 7, 2021 5:23 PM</DIV>
<DIV><B>To:</B> <A title=3Dtriumphs@autox.team.net>list Triumph</A> =
</DIV>
<DIV><B>Subject:</B> [TR] Advice on high compression =
head</DIV></DIV></DIV>
<DIV> </DIV></DIV>
<DIV=20
style=3D'FONT-SIZE: small; TEXT-DECORATION: none; FONT-FAMILY: =
"Calibri"; FONT-WEIGHT: normal; COLOR: #000000; FONT-STYLE: normal; =
DISPLAY: inline'>
<DIV class=3DWordSection1>
<P class=3DMsoNormal>The telenovela =93What=92s going on with this 4A =
cylinder head=94=20
has developed a new plot twist.</P>
<P class=3DMsoNormal><o:p></o:p> </P>
<P class=3DMsoNormal>The head, after cleanup, measures 3.21=94 from =
bottom to the=20
surface for the valve cover gasket. Stock is 3.330 (if I got the number=20
correctly). Some PO cut 0.11 off, because only 0.010=94 was removed in =
this round=20
of clean up. Now I can see an explanation for the persistent pinging =
I=92ve dealt=20
with over the last few years (head has been milled so compression is =
high,=20
material near intake valves has been thinned, increasing likelihood of =
hot spots=20
=96 I=92m getting this from Kastner=92s preparation book), which I had =
thought was due=20
to leaking intakes, carb shafts, or operating at higher =
altitude.<o:p></o:p></P>
<P class=3DMsoNormal><o:p></o:p> </P>
<P class=3DMsoNormal>As is, I can=92t use this head because there is not =
enough=20
slack in the valve train to give 0.010=94 clearance on several valves. I =
didn=92t=20
notice before, but now that I am looking, all the valve adjusters were =
nearly=20
backed out all the way.</P>
<P class=3DMsoNormal><o:p></o:p> </P>
<P class=3DMsoNormal>Looking for advice from the list: is there any =
reasonable way=20
to use this head?</P>
<P class=3DMsoNormal>- I=92d prefer to reduce compression but don=92t =
see any=20
reasonable way to accomplish that. I called GasketWorks and he gently=20
discouraged me from getting a custom thick head gasket, saying instead =
I=92d be=20
better off finding a head which had not been milled so much. </P>
<P class=3DMsoNormal>- Shimming the rocker pedestals to get valve =
clearance feels=20
like a bandaid which certainly won=92t address the pinging (assuming =
that the=20
pinging is a result of the shortened head).</P>
<P class=3DMsoNormal><o:p></o:p> </P>
<P class=3DMsoNormal>Would appreciate any advice on the way forward.</P>
<P class=3DMsoNormal><o:p></o:p> </P>
<P class=3DMsoNormal>Cliff</P>
<P class=3DMsoNormal><o:p></o:p> </P>
<P class=3DMsoNormal>Sent from <A=20
href=3D"https://go.microsoft.com/fwlink/?LinkId=3D550986";>Mail</A> for =
Windows=20
10</P>
<P class=3DMsoNormal><o:p></o:p> </P></DIV>
<P>
<HR>
** triumphs@autox.team.net **<BR><BR>Donate:=20
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