Subject: [TR] Advice on high compression head

From: Cliff Hansen <[email-masked]>
Date: Wed, 7 Apr 2021 21:23:50 +0000

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The telenovela =93What=92s going on with this 4A cylinder head=94 has devel=
oped a new plot twist.

The head, after cleanup, measures 3.21=94 from bottom to the surface for th=
e 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 u=
p. Now I can see an explanation for the persistent pinging I=92ve dealt wit=
h over the last few years (head has been milled so compression is high, mat=
erial near intake valves has been thinned, increasing likelihood of hot spo=
ts =96 I=92m getting this from Kastner=92s preparation book), which I had t=
hought was due to leaking intakes, carb shafts, or operating at higher alti=
tude.

As is, I can=92t use this head because there is not enough slack in the val=
ve train to give 0.010=94 clearance on several valves. I didn=92t notice be=
fore, 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 h=
ead?
- 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 get=
ting a custom thick head gasket, saying instead I=92d be better off finding=
 a head which had not been milled so much.
 - Shimming the rocker pedestals to get valve clearance feels like a bandai=
d which certainly won=92t 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 Window=
s 10

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<p class=3D"MsoNormal">The telenovela =93What=92s going on with this 4A cyl=
inder head=94 has developed a new plot twist.</p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">The head, after cleanup, measures 3.21=94 from botto=
m to the surface for the valve cover gasket. Stock is 3.330 (if I got the n=
umber correctly). Some PO cut 0.11 off, because only 0.010=94 was removed i=
n 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 intak=
e valves has been thinned, increasing likelihood of hot spots =96 I=92m get=
ting this from Kastner=92s preparation book),
 which I had thought was due to leaking intakes, carb shafts, or operating =
at higher altitude.<o:p></o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">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 valve=
s. I didn=92t notice before, but now that I am looking, all the valve adjus=
ters were nearly backed out all the way.</p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">Looking for advice from the list: is there any reaso=
nable way to use this head?</p>
<p class=3D"MsoNormal">- 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=92=
d be better off finding a head which had
 not been milled so much. </p>
<p class=3D"MsoNormal">&nbsp;- Shimming the rocker pedestals to get valve c=
learance feels like a bandaid which certainly won=92t address the pinging (=
assuming that the pinging is a result of the shortened head).</p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">Would appreciate any advice on the way forward.</p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">Cliff</p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">Sent from <a href=3D"https://go.microsoft.com/fwlink=
/?LinkId=3D550986">
Mail</a> for Windows 10</p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
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