<div dir="ltr"><div>Although it feels strange, I will beg to differ with Ron: Clearance is <b>measured at the valve</b>, but you are really setting the clearance <b>at the cam and follower</b>. Because it is not feasible to measure at the cam/follower, if the rocker ratio is higher you must allow for this and set greater clearance at the valve to compensate. Stock rockers are 1.25 or 1.3 or something like that. To correct for 1.5 rockers you should actually multiply the standard clearance by 1.5/1.25 which is 1.2. 1.2 times12 gives us a corrected clearance of 14.4thou. That said, this is not a terribly critical setting and depending on the engine build could be a few thou more. <br></div>Hal<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Oct 31, 2015 at 5:00 PM, Ron Soave via Spridgets <span dir="ltr"><<a href="mailto:spridgets@autox.team.net" target="_blank">spridgets@autox.team.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto"><div>It doesn't. <br><br>Ron Soave</div><div><div class="h5"><div><br>On Oct 31, 2015, at 6:16 PM, Rick Fisk via Spridgets <<a href="mailto:spridgets@autox.team.net" target="_blank">spridgets@autox.team.net</a>> wrote:<br><br></div><blockquote type="cite"><div><div>Why does increasing the rocker ratio cause a need for more clearance?<br><br>Sent from my keyboard</div><div><br>On Oct 31, 2015, at 6:14 PM, Michael Rowe via Spridgets <<a href="mailto:spridgets@autox.team.net" target="_blank">spridgets@autox.team.net</a>> wrote:<br><br></div><blockquote type="cite"><div>
<div><font face="Arial">I used Minisport roller rockers bought cheap in the
2008-9 crash. I no longer remember, but they probably are 1.5
(red), and I also used a "warm" Elgin cam that came in a box of
parts.</font></div>
<div><font face="Arial"></font> </div>
<div><span>Where <a href="http://www.spridgetmania.com/part/C-AHT436/Roller-Tipped-15-Ratio-Rockers-Aluminum" target="_blank">higher
ratio rockers</a> are to be used, the required valve clearance can then be
assessed using this simple formula. For instance when using 1.5 rockers, you
obviously need to multiply the cam/follower clearance by 1.5. So 0.010-in x 1.5
gives 0.015-in for standard/mild cams and 0.012-in x 1.5 gives 0.018-in for
race/more-modified cams. Interestingly, most re-profiled performance cams
generally have a suggested valve clearance of 0.016-in with standard ratio
rockers. To assess required valve clearance where higher ratio rockers are used
simply work it backwards and multiply by the higher ratio. This works out as
0.016-in divided by 1.25 = 0.0128, then x 1.5 = 0.0192" - or 0.019" at the
valve.</span></div>
<blockquote style="BORDER-LEFT:#000000 2px solid;PADDING-LEFT:5px;PADDING-RIGHT:0px;MARGIN-LEFT:5px;MARGIN-RIGHT:0px" dir="ltr">
<div style="FONT:10pt arial">----- Original Message ----- </div>
<div style="FONT:10pt arial;BACKGROUND:#e4e4e4"><b>From:</b>
<a title="rrengineer.mike@att.net" href="mailto:rrengineer.mike@att.net" target="_blank">Michael
MacLean</a> </div>
<div style="FONT:10pt arial"><b>To:</b> <a title="refisk@chartermi.net" href="mailto:refisk@chartermi.net" target="_blank">Rick Fisk</a> ; <a title="mdrowe@optonline.net" href="mailto:mdrowe@optonline.net" target="_blank">Michael Rowe</a>
</div>
<div style="FONT:10pt arial"><b>Cc:</b> <a title="spridgets@autox.team.net" href="mailto:spridgets@autox.team.net" target="_blank">Spridgets</a> </div>
<div style="FONT:10pt arial"><b>Sent:</b> Saturday, October 31, 2015 4:49
PM</div>
<div style="FONT:10pt arial"><b>Subject:</b> Re: [Spridgets] rocker
clearance</div>
<div><br></div>
<div style="BACKGROUND-COLOR:#fff;FONT-FAMILY:times new roman,new york,times,serif;COLOR:#000;FONT-SIZE:16px">
<div>How about when you have 1.5 rocker
arms? Drove the Bugeye around yesterday. Runs great, still blue
smoke on acceleration on a recent rebuild. At leat 1000 miles since
rebuild. I'm afraid the rings never seated properly. Not sure of
the cylinder wall surface during the rebuild as I did not so that part of
it.<br></div>
<div dir="ltr">Mike MacLean<br></div>
<div><span></span></div><br>
<div><br><br></div>
<div style="DISPLAY:block">
<div style="FONT-FAMILY:times new roman,new york,times,serif;FONT-SIZE:16px">
<div style="FONT-FAMILY:HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif;FONT-SIZE:16px">
<div dir="ltr"><font face="Arial" size="2">On Saturday, October 31, 2015 1:26 PM,
Rick Fisk via Spridgets <<a href="mailto:spridgets@autox.team.net" target="_blank">spridgets@autox.team.net</a>>
wrote:<br></font></div>
<blockquote style="BORDER-LEFT:rgb(16,16,255) 2px solid;MARGIN-TOP:5px;PADDING-LEFT:5px;MARGIN-LEFT:5px"><br><br>
<div>
<div>
<div>
<div>The 0.029 in. spec is a whole different thing used when you are
assembling the engine. If your engine is together and you just want to
set the valve clearance it should be 0.012 in. set cold.<br clear="none"><br clear="none">Sent from my keyboard</div>
<div>
<div><br clear="none">On Oct 31, 2015, at 4:06 PM, Michael Rowe via Spridgets
<<a href="mailto:spridgets@autox.team.net" shape="rect" rel="nofollow" target="_blank">spridgets@autox.team.net</a>>
wrote:<br clear="none"><br clear="none"></div>
<blockquote type="cite">
<div></div></blockquote></div></div>
<div>
</div>
<div>
<div>
<div><font face="Arial">New 1275 engine.</font></div>
<div><font face="Arial">Haynes says "Rocker clearance, timing only
= 0.029 in.</font></div>
<div><font face="Arial">My mechanic/tutor says, "that is twice what it should
be."</font></div>
<div><font face="Arial">Bentley says:</font></div>
<div><font face="Arial">Rocker clearance: Running (Standard) = 0.012 in.
cold</font></div>
<div><font face="Arial">
Running (competition work) = 0.015
in.</font></div>
<div><font face="Arial">
timing = 0.029 in.</font></div>
<div><font face="Arial">Online sites agree on = .012 in.
cold.</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">So what is the 0.029 in. for?</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">Michael Rowe</font></div></div>
<blockquote type="cite">
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