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<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=384441017-30122016>Duncan wrote :".... how far downstream of the exhaust
valves is the Lambda sensor installed..." : this may well be the culprit. It is
installed at 130cm/4ft of the exhaust valves because of the long primaries and
secondaries of the exhaust. The Lambda sensor is part of the dyno. Exposed on
the open air it is reading 22.37 so I suppose it is working correctly. I can't
find any leaks on inlet and exhaust side. The engine is running sweetly and
crispy, so I wonder if I get a false ARF reading. Can the distance to the
exhaust valves have such an influence on the ARF reading?</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=384441017-30122016>In fact, also at lower RPM the ARF is much too
lean, but that can be corrected by turning out the idle screws way too far
(4 complete turns or more!), so I was misleading you by speaking of "leaning out
at the higher RPM."</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=384441017-30122016>Should I install the Lambda sensor in one of the
primary or secondary exhaust pipes (and check the spark plugs if they all get
the same mixture strength)?</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=384441017-30122016>Marcel</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=384441017-30122016></SPAN></FONT> </DIV><BR>
<DIV lang=nl class=OutlookMessageHeader dir=ltr align=left>
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<FONT size=2 face=Tahoma><B>Van:</B> Duncan Charlton
[mailto:duncan.charlton54@gmail.com] <BR><B>Verzonden:</B> vrijdag 30 december
2016 13:53<BR><B>Aan:</B> Van Mulders Marcel<BR><B>CC:</B> Duncan Charlton via
Fot<BR><B>Onderwerp:</B> Re: [Fot] TR6 race engine with 45DCOE triple
Webers<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV>How far downstream of the exhaust valves is the Lambda sensor installed,
and how far from the exhaust system outlet is it? You mentioned having
checked for air leaks, but didn’t say whether you checked both intake and
exhaust. Is the dyno operator also using a lambda sensor?</DIV>
<DIV><BR></DIV>
<DIV>This comment is not specific to the TR6 but since it’s leaning out at the
high end I would have initially guessed that your air correction jets are too
large, but one typically expects the AC jet to have a number about 50 higher
than the main jet, whereas your AC jets are nearly the same number as your
original main jets and a lot smaller than your second main jets choice.
<DIV><BR></DIV>
<DIV>According to the Weber choke selection chart the 35mm chokes correspond to
a maximum output of 6000 rpm so 36mm seems fine unless the engine’s desired max
output is a lot higher than that.</DIV>
<DIV><BR></DIV></DIV>
<DIV>
<DIV>
<DIV>Duncan Charlton</DIV>
<DIV>Elgin, Texas USA</DIV>
<DIV><BR></DIV><BR class=Apple-interchange-newline></DIV><BR>
<DIV>
<BLOCKQUOTE type="cite">
<DIV>On Dec 29, 2016, at 3:45 PM, Van Mulders Marcel via Fot <<A
href="mailto:fot@autox.team.net">fot@autox.team.net</A>> wrote:</DIV><BR
class=Apple-interchange-newline>
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<DIV><FONT size=2 face=Arial><SPAN class=885500321-29122016>The engine for a
friend's TR6 racecar is finished at last and it has run a couple of
times now.</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=885500321-29122016>I have a problem
with the mixture : the air correction jets are 155, I started with 140 main
jets but the mixture was much too lean : AFR was 14 at idle and 17 at
5000 rpm. Even with 180 main jets, the AFR is still 15 at 4000 -
5000 rpm. The engine is 2720 cc and 12.6 volumetric CR.</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=885500321-29122016>The Webers are
secondhand, 45DCOE type 152 and they look as new</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=885500321-29122016>The venturis are
36mm, emulsion tubes are F16, idle jets 55F8 and aux. venturis are 4.5. Pump
jets are 40 without a bleed hole. The plugs have a correct colour, no
sooting, no signs of overheating. The engine is on a dyno but I didn't risk so
far to really load the engine, so the plugs doesn't tell much. The lambda
sensor is a wide Bosch sensor, about new and with an Innovate controller. I
suppose 180 main jets are already too big. I can't find any air leaks and the
spark plugs have all the same colour. Is it possible that 36mm chokes are too
big? Any idea's why the mixture can be too lean, even with 180 main jets?
Should I suspect the lambda sensor/Innovate controller? What venturis
should I start with? </SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=885500321-29122016>Another question :
I have no experience about the range of total ignition advance a full race TR6
engine does need.</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=885500321-29122016>Marcel
</SPAN></FONT></DIV></DIV>_______________________________________________<BR><A
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