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/*]]>*/</style></div><div>Hi Jim,</div><div>The valve guides have an oval shape in the ports, but are not shortened. </div><div>Marcel</div><div><br></div><hr id="zwchr" data-marker="__DIVIDER__"><div data-marker="__HEADERS__"><b>Van: </b>"Jim Gray" <toodamnfunky@comcast.net><br><b>Aan: </b>"van mulders marcel" <van.mulders.marcel@telenet.be>, "tr4racing" <tr4racing@googlemail.com><br><b>Cc: </b>"fot" <fot@autox.team.net><br><b>Verzonden: </b>Zaterdag 2 mei 2020 23:30:42<br><b>Onderwerp: </b>RE: [Fot] Valve overlap and compression test<br></div><div><br></div><div data-marker="__QUOTED_TEXT__"><div class="WordSection1"><p class="MsoNormal">Marcel,</p><p class="MsoNormal">By any chance do you flush out your valve guides in the ports? The reason I ask is it raises hell with the valve grinder when they try to get a good square grind</p><p class="MsoNormal">for some reason.</p><p class="MsoNormal">jim g</p><p class="MsoNormal"> </p><div><div style="border:none;border-top:solid #e1e1e1 1pt;padding:3pt 0in 0in 0in"><p class="MsoNormal"><b>From:</b> Fot <fot-bounces@autox.team.net> <b>On Behalf Of </b>van.mulders.marcel--- via Fot<br><b>Sent:</b> Saturday, May 2, 2020 2:30 PM<br><b>To:</b> tr4racing <tr4racing@googlemail.com><br><b>Cc:</b> fot <fot@autox.team.net><br><b>Subject:</b> Re: [Fot] Valve overlap and compression test</p></div></div><p class="MsoNormal"> </p><div><div><p class="MsoNormal"><span style="font-size:10pt;font-family:'verdana' , sans-serif;color:black">Hallo Chris,</span></p></div><div><p class="MsoNormal"><span style="font-size:10pt;font-family:'verdana' , sans-serif;color:black">of course the cylinderhead has to be repaired. I think the man who has put the big valves in it, has taken too much risks : the valve seats (the rings that are pressed into the cyl head) are small where they do meet, and maybe the seats are distorted a bit because of this, but I don't know for sure, I will see when pulling the head. I know one cannot change the valve clearance too much, but maybe 0.05mm more valve lash is ok and it will reduce the valve overlap. I believe 110° overlap is a lot, even for a racecamshaft. Any idea's someone about that? The compression test with increased valve lash is much higher than with the recommended valve lash : I wonder if it is making any sense at all to check the compression of a race engine without increasing the valve lash : with the normal clearances, the inlet valve is closing when the piston has already travelled a lot upwards, hence the big difference between the compression test results with normal and with increased valve lash. So I think, if you want to test the compression, you have to increase the valve lash firstly(at least when the engine has a race camshaft).</span></p></div><div><p class="MsoNormal"><span style="font-size:10pt;font-family:'verdana' , sans-serif;color:black">Marcel</span></p></div><div><p class="MsoNormal"><span style="font-size:10pt;font-family:'verdana' , sans-serif;color:black"> </span></p></div><div class="MsoNormal" align="center" style="text-align:center"><span style="font-size:10pt;font-family:'verdana' , sans-serif;color:black"><hr size="2" width="100%" align="center" id="zwchr"></span></div><div><p class="MsoNormal"><b><span style="font-size:10pt;font-family:'verdana' , sans-serif;color:black">Van: </span></b><span style="font-size:10pt;font-family:'verdana' , sans-serif;color:black">"fot" <<a href="mailto:fot@autox.team.net" target="_blank" rel="nofollow noopener noreferrer">fot@autox.team.net</a>><br><b>Aan: </b>"fot" <<a href="mailto:fot@autox.team.net" target="_blank" rel="nofollow noopener noreferrer">fot@autox.team.net</a>><br><b>Verzonden: </b>Zaterdag 2 mei 2020 21:29:59<br><b>Onderwerp: </b>Re: [Fot] Valve overlap and compression test</span></p></div><div><p class="MsoNormal"><span style="font-size:10pt;font-family:'verdana' , sans-serif;color:black"> </span></p></div><div><p class="MsoNormal"><span lang="DE" style="color:black">Hello Marcel,</span><span style="color:black"></span></p><p class="MsoNormal"><span lang="DE" style="color:black"> </span><span style="color:black"></span></p><p class="MsoNormal"><span style="color:black">Your engine has leaking valves.</span></p><p class="MsoNormal"><span style="color:black">It won’t get better from changing measurement procedures.</span></p><p class="MsoNormal"><span style="color:black">Maybe the seat is rough, or the valves bent, or offset .</span></p><p class="MsoNormal"><span style="color:black">Something to make sure about.</span></p><p class="MsoNormal"><span style="color:black"> </span></p><p class="MsoNormal"><span style="color:black">Enlarging the valve leash could result in hammering everything dead in the valve train.</span></p><p class="MsoNormal"><span style="color:black"> </span></p><p class="MsoNormal"><span style="color:black">Cheers</span></p><p class="MsoNormal"><span style="color:black">Chris</span></p><p class="MsoNormal"><span style="color:black"> </span></p><div><div style="border:none;border-top:solid #e1e1e1 1pt;padding:3pt 0in 0in 0in"><p class="MsoNormal"><b><span lang="DE" style="color:black">Von:</span></b><span lang="DE" style="color:black"> Fot <<a href="mailto:fot-bounces@autox.team.net" target="_blank" rel="nofollow noopener noreferrer">fot-bounces@autox.team.net</a>> <b>Im Auftrag von </b>van.mulders.marcel--- via Fot<br><b>Gesendet:</b> Samstag, 2. Mai 2020 14:43<br><b>An:</b> fot <<a href="mailto:fot@autox.team.net" target="_blank" rel="nofollow noopener noreferrer">fot@autox.team.net</a>><br><b>Betreff:</b> [Fot] Valve overlap and compression test</span><span style="color:black"></span></p></div></div><p class="MsoNormal"><span style="color:black"> </span></p><div><div><p class="MsoNormal"><span style="font-size:10pt;font-family:'verdana' , sans-serif;color:black">A leaking test on my TR6 engine is showing a leaking exhaust valve on cyl no 1 (48% on the gauge of the device) and a leaking inlet valve on cyl no 2 (75%). Compression on cyl no1 is 9.5 bar and on cyl 2 it is 8 bar. The compression on the other cylinders is between 12 and 13.5 bar. This is with a race cam with a valve overlap of 110° (320-F grind). Because of the high overlap, the piston has risen a lot before the inlet valve is closed, so I did the compression test again, but with a valve lash of 2.5mm/0.1" : compression went from 9.5 bar to 14.5 on cyl no 1 and from 8 bar to 15 on cyl no 2. With this valve lash, the compression on the other cylinders went up to 16 - 18.5 bar. Of course, when the engine is running at high rpm, a lot of valve overlap is necessary for best cylinder filling, but I wonder if 110° isn't too much?? The recommended valve lash is 0.40mm/0.016" when the rocker ratio is 1.45(0.43mm/ with my 1.55 roller rockers). Would it be risky to set the valve lash at some 0.05mm/0.002" higher?</span><span style="color:black"></span></p></div><div><p class="MsoNormal"><span style="font-size:10pt;font-family:'verdana' , sans-serif;color:black">PS : is it common practice to set the valve lash at a couple of mm to perform a compression test, because it seems that the valve lash has a lot of influence on the result when testing a race camshaft?</span><span style="color:black"></span></p></div><div><p class="MsoNormal"><span style="font-size:10pt;font-family:'verdana' , sans-serif;color:black">Marcel</span><span style="color:black"></span></p></div></div><p class="MsoNormal"><span style="font-size:10pt;font-family:'verdana' , sans-serif;color:black"><br>_______________________________________________<br><a href="mailto:fot@autox.team.net" target="_blank" rel="nofollow noopener noreferrer">fot@autox.team.net</a><br><br><a href="http://www.fot-racing.com" target="_blank" rel="nofollow noopener noreferrer">http://www.fot-racing.com</a><br><br>Donate: <a href="http://www.team.net/donate.html" target="_blank" rel="nofollow noopener noreferrer">http://www.team.net/donate.html</a><br>Archive: <a href="http://autox.team.net/archive" target="_blank" rel="nofollow noopener noreferrer">http://autox.team.net/archive</a> <a href="http://www.team.net/pipermail/fot" target="_blank" rel="nofollow noopener noreferrer">http://www.team.net/pipermail/fot</a><br>Unsubscribe/Manage: <a href="http://autox.team.net/mailman/options/fot/van.mulders.marcel@telenet.be" target="_blank" rel="nofollow noopener noreferrer">http://autox.team.net/mailman/options/fot/van.mulders.marcel@telenet.be</a></span></p></div></div></div><br></div></div></body></html>