<div dir="ltr"><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">My long time friend Dick Paterson runs one of the fastest vintage mini racers in North America. <br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Watch him, car #97, in this race at 13.00 mins :<br><a href="https://www.youtube.com/watch?v=iNRAnvaWguc&list=PLItkgEMb_qyy_NEDpyTjd9c0PIe2vXeHV&index=3">https://www.youtube.com/watch?v=iNRAnvaWguc&list=PLItkgEMb_qyy_NEDpyTjd9c0PIe2vXeHV&index=3</a><br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">In 2014, after running bronze guides for many years, he had a catastrophic engine blow up and the cause was traced to the bronze exhaust guides seizing to the valves. <br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">You could not pay him enough money to change back to bronze guides today..If it doesn't get you this season it will eventually!!<br><br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Michael S<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">BN1 #174<br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Mar 29, 2015 at 3:20 PM, Austin Healey <span dir="ltr"><<a href="mailto:pajtamuvek@gmail.com" target="_blank">pajtamuvek@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">I am not deep into maths, but have some experience with bronze guides. We use them without problems in race mini engines. The key is to use less interference fit compared to iron guides. And of course set the system to bigger cold clearance.<div><br></div><div>Gergo</div></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">2015-03-29 17:01 GMT+02:00 Michael Salter <span dir="ltr"><<a href="mailto:michaelsalter@gmail.com" target="_blank">michaelsalter@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small"><span>Oops, small miscalculation there... Where I wrote: <br><i>So, if the wall of our guide is presumed to have an area of only 600 sq
mm. (0.1 sq in), it would take 4276 kg (9427lbf)to distort or deform it.</i><br></span>I should have written:<br><i>So, if the wall of our guide is presumed to have an area of only 600 sq
mm. (0.1 sq in), it would take 6042kg (13,329 lbf) [4276 kg (9427lbf) x 1.414 (root 2)] to distort or deform it.
</i><br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">I think;... because a compression failure would be considered to be a shear failure at 45 degrees. <br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">I'm sure there are people out there who are better at these calculations than I am from whom I would welcome comment.<br><br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Michael S<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">BN1 #174<br></div></div><div><div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Mar 29, 2015 at 10:49 AM, Michael Salter <span dir="ltr"><<a href="mailto:michaelsalter@gmail.com" target="_blank">michaelsalter@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Ok Gergo, <br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">We are making progress....<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">From your answer I believe that you would concur that both the ID and the OD of an unrestrained guide would increase as it is heated . i.e. thermal expansion.<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">However, you conclude that solids are, to quote, "not that "solid" as they may look". <br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">From that statement I presume that you are indicating that the solid material of the guide distorts or deforms because it is constrained by the hole in the cylinder head.<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Now I would ask you to refer to this video from Purdue University College of Technology: <br><a href="https://www.youtube.com/watch?v=V6D3QgdO5Bk" target="_blank">https://www.youtube.com/watch?v=V6D3QgdO5Bk</a><br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">If you are not into the mathematics just skip to 6:45 for the result.<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">371,000 lbs (168tonnes)!!!<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Now check the structural strength of bronze... of course it varies a little with different alloys but a yield strength of 650 Mpa ( 94274 p.s.i.) is typical.<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">The mathematics required to use these numbers to calculate the forces required to radially crush a cylinder (i.e. our valve guide) are a little complex but be assured the numbers are MASSIVE.<br>So, if the wall of our guide is presumed to have an area of only 600 sq mm. (0.1 sq in), it would take 4276 kg (9427lbf)to distort or deform it. <br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Now, armed with that knowledge please read my <a href="http://www.netbug.net/blogmichael/?p=384" target="_blank">blog post</a> carefully and you may have an inkling for why I strongly advise against the use of bronze guides in a cast iron head.<br><br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Michael S<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small"><br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small"><br><br><br><br></div></div><div><div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Mar 29, 2015 at 3:25 AM, Austin Healey <span dir="ltr"><<a href="mailto:pajtamuvek@gmail.com" target="_blank">pajtamuvek@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Yes. This is happening. The head material expands less, the guide expand more, and thus it has to go somewhere. Metals are not that "solid" as they might look like.<div><br></div><div>Gergo</div></div><div><div><div class="gmail_extra"><br><div class="gmail_quote">2015-03-29 4:09 GMT+02:00 Michael Salter <span dir="ltr"><<a href="mailto:michaelsalter@gmail.com" target="_blank">michaelsalter@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">So Gergo, <br>if I understand you correctly in a situation where the guide was not installed in a head and it was then heated the outside diameter and for that matter the inside diameter of the guide would increase due to thermal expansion....correct?<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">However, the difference, when the guide is installed in the head is that the head material, i.e. the hole that the guide is installed in, would prevent the guide from expanding or, expressed another way, because the hole in the head would not increase in diameter as much as the guide would increase in diameter the head material would effectively compress the guide and prevent it from expanding..... correct?<br><br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Michael S<br></div></div><div><div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Mar 28, 2015 at 4:38 PM, Austin Healey <span dir="ltr"><<a href="mailto:pajtamuvek@gmail.com" target="_blank">pajtamuvek@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Yes it does. The material has to expand somewhere. It cant go in the oposite direction.<div><br></div><div>g</div></div><div><div><div class="gmail_extra"><br><div class="gmail_quote">2015-03-28 20:12 GMT+01:00 Michael Salter <span dir="ltr"><<a href="mailto:michaelsalter@gmail.com" target="_blank">michaelsalter@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Hi Gergo, <br>just so I'm clear...you are suggesting that the internal diameter of the guide will get smaller as it heats up therefore that extra clearance is required?<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Michael S<br></div></div><div><div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Mar 28, 2015 at 3:08 AM, Austin Healey <span dir="ltr"><<a href="mailto:pajtamuvek@gmail.com" target="_blank">pajtamuvek@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Bronze guides expand more when they heat up. Thats why You have to use greater clearance. But when they work, the clearance will be the same. Worn out guides have two negative side effects: oil consumption, and premature wear on the valves as they dissipate heat slower due to rocking on the valve seat. The exhaust guides are more prone to oil consumption, exhaust guides are more prone to overheating.<div><br></div><div>Gergo</div></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div>2015-03-27 20:01 GMT+01:00 Michael Salter <span dir="ltr"><<a href="mailto:michaelsalter@gmail.com" target="_blank">michaelsalter@gmail.com</a>></span>:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div><div dir="ltr"><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Hi Raymond, <br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">The factory specification calls for 0.0025 to 0.0015 clearance for the inlets and 0.002 to 0.001 clearance for the exhausts if you are using cast iron guides however if you are using bronze THAT WILL NOT WORK!!!<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">To be safe with bronze guides you will have to hog them out to about 0.006" clearance..which means there is really no point in replacing them.<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">I would point you to <a href="http://www.netbug.net/blogmichael/?p=384" target="_blank">this article</a> on my blog...been there done that...<br><br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">Michael S<br></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif;font-size:small">BN1 #174<br></div></div><div class="gmail_extra"><br><div class="gmail_quote"><span>On Fri, Mar 27, 2015 at 2:17 PM, RAYMOND SMITHSON <span dir="ltr"><<a href="mailto:rjsmithson@shaw.ca" target="_blank">rjsmithson@shaw.ca</a>></span> wrote:<br></span><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span><div><div style="font-family:arial,helvetica,sans-serif;font-size:10pt;color:#000000">I am rebuilding my 3000 cylinder head and have found the inlet valve stems have .008" clearance but the exhaust stems have only .002" clearance. Does anyone know if this is common?</div></div><br></span>_______________________________________________<br>
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</blockquote></div><br><br clear="all"><br>-- <br><div><div dir="ltr"><div><div dir="ltr"><i><font><span style="color:black">If you can't fix it with a hammer, you've got an electrical problem.</span></font></i><br><br><div></div><div></div><div></div></div></div></div></div>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br><div><div dir="ltr"><div><div dir="ltr"><i><font><span style="color:black">If you can't fix it with a hammer, you've got an electrical problem.</span></font></i><br><br><div></div><div></div><div></div></div></div></div></div>
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</div></div></blockquote></div><br></div>
</div></div></blockquote></div><br><br clear="all"><br>-- <br><div><div dir="ltr"><div><div dir="ltr"><i><font><span style="color:black">If you can't fix it with a hammer, you've got an electrical problem.</span></font></i><br><br><div></div><div></div><div></div></div></div></div></div>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br><div><div dir="ltr"><div><div dir="ltr"><i><font><span style="color:black">If you can't fix it with a hammer, you've got an electrical problem.</span></font></i><br><br><div></div><div></div><div></div></div></div></div></div>
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</div></div></blockquote></div><br></div>
</div></div></blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><i><font><span style="color:black">If you can't fix it with a hammer, you've got an electrical problem.</span></font></i><br><br><div></div><div></div><div></div></div></div></div></div>
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