Subject: [Spridgets] Forged rockers and Hardened Shaft

From: Michael MacLean via Spridgets <[email-masked]>
Date: Wed, 20 Dec 2023 06:25:21 -0800

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     I acquired a set of forged rockers and a hardened rocker shaft from
David Anton to "build" a new rocker arm assembly.  This is for the new
engine I am building to replace the rod knocking 1275 in my Bugeye.  For
what it costs, I am committed to put this assembly together.  The one
caveat that David told me when he sold me the set of shaft and rockers was
that the rocker bushes had to be honed to fit the shaft.  The hardening
process had increased the diameter of the shaft by a couple of thousands.
Not a problem.  I found a local shop that can do it.  The rockers should
have a clearance of 1 -2 thou for proper lubrication.  The one thing I did
not take into account was the pillars.  Should they be honed also?  I can
find no indication anywhere of the clearance dimension for the shaft to
pillar fit. Knowing that a tight fit will produce failure and too loose of
a fit will drop oil pressure.  A question for you engine builders out there.
Mike MacLean

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<div dir=3D"ltr"><div>=C2=A0=C2=A0=C2=A0=C2=A0 I acquired a set of forged r=
ockers and a hardened rocker shaft from David Anton to &quot;build&quot; a =
new rocker arm assembly.=C2=A0 This is for the new engine I am building to =
replace the rod knocking 1275 in my Bugeye.=C2=A0 For what it costs, I am c=
ommitted to put this assembly together.=C2=A0 The one caveat that David tol=
d me when he sold me the set of shaft and rockers was that the rocker bushe=
s had to be honed to fit the shaft.=C2=A0 The hardening process had increas=
ed the diameter of the shaft by a couple of thousands.=C2=A0 Not a problem.=
=C2=A0 I found a local shop that can do it.=C2=A0 The rockers should have a=
 clearance of 1 -2 thou for proper lubrication.=C2=A0 The one thing I did n=
ot take into account was the pillars.=C2=A0 Should they be honed also?=C2=
=A0 I can find no indication anywhere of the clearance dimension for the sh=
aft to pillar fit. Knowing that a tight fit will produce failure and too lo=
ose of a fit will drop oil pressure.=C2=A0 A question for you engine builde=
rs out there.</div><div>Mike MacLean=C2=A0 <br></div></div>

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[email-masked]

Archive: http://www.team.net/pipermail/spridgets  http://autox.team.net/archive

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From: GUY DAY via Spridgets <[email-masked]>
Date: Fri, 22 Dec 2023 00:48:02 +0000 (GMT)

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Hi Mike,
Short answer - no.  Don't read further unless you have time to spare.
Time to ask you a question - what is the purpose of 'honing'?  Save you 
thinking (lol), it is to improve the regularity of the surface both in 
its geometric shape and its surface finish.  (I always thought it was to 
make it rounder and smoother but - what do I know.)  So it improves a 
moving contact between a couple of lumps of metal.  ie piston rings to 
bore or, rocker shaft to rockers.  It reduces friction and enables a 
larger surface to surface contact area.Honing reduces friction to a 
minimal amount - so ask, does your rocker shaft rotate in the pillars or 
do they hold it nice and rigid preventing unwanted fluctuating movements 
in a precisely calculated rocker arm movement and position?  The pillars 
hold it still.  So, as a general, background thought - if they are 
moving, hone it and if they don't move against each other don't bother. 
Now this is not a rule, various surfaces (ie head to block or manifold 
flanges to block) do need a tad of honing to make them seat properly and 
some extreme honing comes under the guise of 'polishing' but that 
doesn't generally improve the geometric qualities - but it can.  It is 
just a rather loose basic principle.

Have a Merry Christmas and a Happy New Year

------ Original Message ------
From: "Michael MacLean via Spridgets" <[email-masked]>
To: "Spridgets" <[email-masked]>
Sent: Wednesday, 20 Dec, 23 At 14:25
Subject: [Spridgets] Forged rockers and Hardened Shaft

      I acquired a set of forged rockers and a hardened rocker shaft 
from David Anton to "build" a new rocker arm assembly.  This is for the 
new engine I am building to replace the rod knocking 1275 in my Bugeye. 
For what it costs, I am committed to put this assembly together.  The 
one caveat that David told me when he sold me the set of shaft and 
rockers was that the rocker bushes had to be honed to fit the shaft. 
The hardening process had increased the diameter of the shaft by a 
couple of thousands.  Not a problem.  I found a local shop that can do 
it.  The rockers should have a clearance of 1 -2 thou for proper 
lubrication.  The one thing I did not take into account was the pillars. 
Should they be honed also?  I can find no indication anywhere of the 
clearance dimension for the shaft to pillar fit. Knowing that a tight 
fit will produce failure and too loose of a fit will drop oil pressure. 
A question for you engine builders out there.
Mike MacLean

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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org=
/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns=3D"http://www.w3.org/1999/xh=
tml"> <head> <meta http-equiv=3D"Content-Type" content=3D"text/html; charse=
t=3DUTF-8" /> </head> <body><div class=3D"auto-created-dir-div" dir=3D"auto=
" style=3D"unicode-bidi: embed;">Hi Mike,<div><p>Short answer - no.  Don&#3=
9;t read further unless you have time to spare.</p><div><p>Time to ask you =
a question - what is the purpose of &#39;honing&#39;?  Save you thinking (l=
ol), it is to improve the regularity of the surface both in its geometric s=
hape and its surface finish.  (I always thought it was to make it rounder a=
nd smoother but - what do I know.)  So it improves a moving contact between=
 a couple of lumps of metal.  ie piston rings to bore or, rocker shaft to r=
ockers.  It <span style=3D"display: inline !important;">reduces friction an=
d enables a larger surface to surface contact area.</span></p>Honing reduce=
s friction to a minimal amount - so ask, does your rocker shaft rotate in t=
he pillars or do they hold it nice and rigid preventing unwanted fluctuatin=
g movements in a precisely calculated rocker arm movement and position?  Th=
e pillars hold it still.  So, as a general, background thought - if they ar=
e moving, hone it and if they don&#39;t move against each other don&#39;t b=
other.   Now this is not a rule, various surfaces (ie head to block or mani=
fold flanges to block) do need a tad of honing to make them seat properly a=
nd some extreme honing comes under the guise of &#39;polishing&#39; but tha=
t doesn&#39;t generally improve the geometric qualities - but it can.  It i=
s just a rather loose basic principle.</div><div><p><br></p><p>Have a Merry=
 Christmas and a Happy New Year</p><p><br></p><p><br></p><blockquote style=
=3D"margin: 0 auto;padding: 0 2.0em;border-left: 2.0px solid rgb(0,173,229)=
;"><br><br>------ Original Message ------<br>From: &quot;Michael MacLean vi=
a Spridgets&quot; &lt;<span class=3D"wt_Email">[email-masked]</sp=
an><span></span>&gt;<br>To: &quot;Spridgets&quot; &lt;<span class=3D"wt_Ema=
il">[email-masked]</span><span></span>&gt;<br>Sent: Wednesday, 20=
 Dec, 23 At 14:25<br>Subject: [Spridgets] Forged rockers and Hardened Shaft=
<br><br><div dir=3D"ltr"><div>     I acquired a set of forged rockers and a=
 hardened rocker shaft from David Anton to &quot;build&quot; a new rocker a=
rm assembly.  This is for the new engine I am building to replace the rod k=
nocking 1275 in my Bugeye.  For what it costs, I am committed to put this a=
ssembly together.  The one caveat that David told me when he sold me the se=
t of shaft and rockers was that the rocker bushes had to be honed to fit th=
e shaft.  The hardening process had increased the diameter of the shaft by =
a couple of thousands.  Not a problem.  I found a local shop that can do it=
.  The rockers should have a clearance of 1 -2 thou for proper lubrication.=
  The one thing I did not take into account was the pillars.  Should they b=
e honed also?  I can find no indication anywhere of the clearance dimension=
 for the shaft to pillar fit. Knowing that a tight fit will produce failure=
 and too loose of a fit will drop oil pressure.  A question for you engine =
builders out there.</div><div>Mike MacLean  <br></div></div> <hr>----------=
--------------<br> <br> <span class=3D"wt_Email"><span class=3D"wt_Email">s=
[email-masked]</span><span></span></span><span></span><br> <br> Do=
nate: <a target=3D"_blank" href=3D"http://www.team.net/donate.html">http://=
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 Archive: <a target=3D"_blank" href=3D"http://www.team.net/pipermail/spridg=
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n/options/spridgets/[email-masked]</a><br> </blockquote></div></div><=
/div> </body></html>
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