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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D'>As I said in a different post, I made the mistake of using TDC and BDC too freely, as I meant the TDC and BDC of the cam lobe, and actually that isn’t accurate, it is degrees before and after the top of lobe, which can now call BTL and ATL:<)))) (before top of lobe…) While I agree that the lobe leads in to BTL and follows ATL is still raised over the bottom of the lobe (BL), I know the lobes don’t extend 180 degrees, 70-90 degrees either side of Top Lobe and still keep the follower up all the way. As you then kind of point out, and what my question was, how far TL can be assumed and then whether that lined up 180 degrees opposite the other RON valve. I now understand fully that the follower (I think it’s the right word) will stay on the TL for an extended time or degrees. The last question still remains unstated: does the TL of valve 8 mean that you have found the BL of valve 1? If I remember correctly, they aren’t 180 opposite, input being before or after exhaust by some degrees. Is the difference of opposition so insignificant that it doesn’t matter? Close to TL on one valve is also close enough on the other valve? <o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Hope that is more clear.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Clayton<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b>From:</b> PaulHunt73 [mailto:paulhunt73@virginmedia.com] <br><b>Sent:</b> Tuesday, May 19, 2015 2:22 AM<br><b>To:</b> crk@godblessthe.us; mgs@autox.team.net<br><b>Subject:</b> Re: [Mgs] tappet question<o:p></o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Times New Roman",serif'>As said elsewhere TDC and BDC are not relevant, if you are referring to the piston. If you look at the valve timing the inlet lobe is at its peak 70-odd degrees before BDC, and the exhaust valve is at it's peak about the same distance after BDC. So the back of the lobes are under the followers 180 degrees from there, which is more than 70 degrees before TDC and after TDC respectively.</span><span style='font-size:12.0pt;font-family:"Times New Roman",serif'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman",serif'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Times New Roman",serif'>But it shouldn't make a difference, look at the cam profile, and the base circle should extend for significantly more than half way round the cam, in theory giving more than 180 of engine rotation where the clearance should be the same.</span><span style='font-size:12.0pt;font-family:"Times New Roman",serif'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman",serif'> <o:p></o:p></span></p></div><div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Times New Roman",serif'>Note in theory, which is why I said it's one of the reasons why I find the position of greatest gap to adjust them, which on mine (and others I have done) can be several degrees either side of the strict RON point. </span><span style='font-size:12.0pt;font-family:"Times New Roman",serif'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman",serif'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Times New Roman",serif'>Also, whilst the dynamic forces on the piston etc. are slightly different on compression and expansion etc, statically TDC is directly above BDC, how could it be anything else?</span><span style='font-size:12.0pt;font-family:"Times New Roman",serif'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman",serif'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Times New Roman",serif'>PaulH.</span><span style='font-size:12.0pt;font-family:"Times New Roman",serif'><o:p></o:p></span></p></div></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman",serif'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Times New Roman",serif'> </span><span style='font-size:12.0pt;font-family:"Times New Roman",serif'>----- Original Message ----- <o:p></o:p></span></p></div><blockquote style='border:none;border-left:solid black 1.5pt;padding:0in 0in 0in 4.0pt;margin-left:3.75pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman",serif'><o:p> </o:p></span></p></div><p class=MsoNormal><span style='color:#1F497D'>Regarding Rule of Nine, I understand having 8 all the way up to set 1. But there is a significant rotation between “real close to the top” in front of, and after TDC. This can be seen with rotation the engine and seeing very little to no movement. Also, if I am not mistaken 8 TDC is not perfectly in line with BDC of 1; there is a bias. This means that when 8 is TDC, 1 is not absolutely BDC ready for measurement. So the question is, how do you ensure, with all of that slop, that you truly have BDC?<o:p></o:p></span></p></blockquote></div></body></html>