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<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=733074207-18092015>Thanks to all of you for the usefull
information.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><SPAN class=733074207-18092015></SPAN><SPAN
class=733074207-18092015></SPAN><FONT face=Arial><FONT color=#0000ff><FONT
size=2>3<SPAN class=733074207-18092015>5kgs seat pressure seem to
be too low : with shimming, 50kgs/110lbs is possible without risking coil
binding and the nose pressure will then be 120kgs/265lbs. For the cylinderhead
with 25kgs seat pressure, I've to look for new
springs.</SPAN></FONT></FONT></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT color=#0000ff><FONT size=2><SPAN
class=733074207-18092015> I've been weighing the parts of the drive train
:</SPAN></FONT></FONT></FONT></DIV>
<DIV dir=ltr align=left><SPAN class=733074207-18092015></SPAN><SPAN
class=733074207-18092015></SPAN><FONT face=Arial><FONT color=#0000ff><FONT
size=2>D<SPAN class=733074207-18092015>epending on what push rods are used,
minimum weight is 380 g, maximum is 420g! ( half of the weight of the springs
and the rockers is taken into account). My heaviest 'race' pushrods are 130
g, the lightest are</SPAN></FONT></FONT></FONT></DIV>
<DIV dir=ltr align=left><SPAN class=733074207-18092015></SPAN><SPAN
class=733074207-18092015></SPAN><FONT face=Arial><FONT color=#0000ff><FONT
size=2>s<SPAN class=733074207-18092015>till 90g. Standard pushrods are about 73
g : I wonder if these pushrods are strong
enough?</SPAN></FONT></FONT></FONT></DIV>
<DIV dir=ltr align=left><SPAN class=733074207-18092015></SPAN><SPAN
class=733074207-18092015></SPAN><FONT face=Arial><FONT color=#0000ff><FONT
size=2>I<SPAN class=733074207-18092015> forgot about the valve train for years,
it's strange and maybe it's the same for you , but I always have blind
spots for some area's of my race car.</SPAN></FONT></FONT></FONT></DIV>
<DIV dir=ltr align=left><SPAN class=733074207-18092015></SPAN><SPAN
class=733074207-18092015></SPAN><FONT face=Arial><FONT color=#0000ff><FONT
size=2>M<SPAN
class=733074207-18092015>arcel</SPAN></FONT></FONT></FONT><BR></DIV>
<DIV lang=nl class=OutlookMessageHeader dir=ltr align=left>
<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>Van:</B> Fot [mailto:fot-bounces@autox.team.net]
<B>Namens </B>Enquiries Road & Track<BR><B>Verzonden:</B> woensdag 16
september 2015 22:24<BR><B>Aan:</B> fot@autox.team.net<BR><B>Onderwerp:</B>
[Fot] re TR6 Cannon Intake Manifold<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV dir=ltr>re valve seat pressures
<DIV><BR></DIV>
<DIV>valve seat pressures are normally considered as a pair, seat pressure and
nose pressure. more often than not, the cam grinder suggests what "over the
nose" pressure is probably needed and you then work backwards and find the seat
pressure.
<DIV><BR></DIV>
<DIV>you can make small alterations by shimming the bottom of the valve springs.
some brands of springs used to come with suggested shim thicknesses, but in our
engine shop we have a spring rate gauge to work this out<BR>
<DIV><BR></DIV>
<DIV>all of this needs some experimentation and definitely on a cam-by-cam
basis. generalist advice is often not helpful as it might seem</DIV>
<DIV><BR></DIV>
<DIV>spring pressure is not the only consideration for valve float at high revs
so dont become fixated on this. valve train weight, spring interference (inner
to outer) and cam lobe ramp design, are all equally critical issues. </DIV>
<DIV><BR></DIV>
<DIV>in days of old, very high pressures were used , often because the people
involved had no other method of controlling valve bounce at high revs. today,
analysis of working springs using a strobe light and some times high speed
video, ultra light weight valve gear, controlled inner/outer spring
interference, all combine to allow spring rates to fall dramatically on a
modern, highly accurately ground cam <BR>
<DIV><BR></DIV>
<DIV>on a TR6 with the stock "heavy" valves, pushrods & lifters, and an old
design cam something like 250lb over the nose is likely to be needed on a
wild race cam. </DIV>
<DIV><BR></DIV>
<DIV>all of my engines run the lowest possible pressures and the lightest
possible valve train. we have got nose pressure down to 150lb on several TR6
race engines </DIV>
<DIV><BR></DIV>
<DIV>Terry O'Beirne<BR>
<DIV>
<DIV
class=gmail_signature><BR></DIV></DIV></DIV></DIV></DIV></DIV></DIV></BODY></HTML>