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<DIV><FONT face=Arial size=2>Brian, have you experimented with increasing the
pump pressure? Maybe the upline mid-range is starving due to not having enough
fuel but WOT creates enough extra suction to pull the fuel through.
</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>If you haven't already tried this why don't you
increase the pump pressure by 1/4 turn at a time and see if it
helps.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>BTW, you're correct that the throttle is very
non-linear. Once my carb is about half open the engine is much closer to full
throttle than mid throttle. I added a mix to my radio to introduce an expo
behavior with the throttle and this tremendously improved how linear the
throttle response is on my throttle stick. This made the plane much easier to
fly.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Good luck,</FONT></DIV>
<DIV><FONT face=Arial size=2>Keith Black</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=auto7832@bellsouth.net href="mailto:auto7832@bellsouth.net">Brian
Billings</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Thursday, June 05, 2003 2:27
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> MC carb for Webra</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2> Bob, I was very careful
running this motor in, ran several tanks through engine before flying and
monitored the cylinder head temp the whole time. Motor ran great the first
weekend out with the plane but the next weekend motor was having trouble from
the first start of the day and I was unable to fly due to troubles,
sagging mainly. I sent motor to piedmont for check out and they said it ran
fine and had no problems. I can hold engine against compression with no leak
down felt but the discoloration of the ring and top of piston does add
credence to your theory, plus it does seem like there is less compression once
engine has been ran to operating temperature. I would put a piston, ring and
liner in it if I new my problems would go away but I am afraid that it is not
the root of my problem but a outcome of the sagging in
flight. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><BR><FONT face=Arial><FONT size=2>Hi<BR><BR>I'm sticking my nose in here,
but I've been running the Greve (Piedmont) set up for some time now and at
their setting it WORKS, very well. I agree with Jerry, by the way, the
numbers are wrong, based on my theory, but it works so I have not messed with
it. Reading your symptoms, I suspect you have a bad ring, allowing blow
by into the crank case, which changes with temp, which changes the crank case
pressure, which changes the "pump performance", which changes the temp, which
changes........ I have found that long before the ring is worn enough to
cause loss of compression/power it will upset the pump/regulator (speaking of
the OS here) because of combustion blow by into the crankcase. Not
enough leakage to effect peak performance, but with crankcase pressure at 8-12
lbs (I think those are the numbers) and combustion pressure at probably
thousands of lbs a little leakage could double the case pressure and
screw things up. I have found replacing the ring sometimes ring and
cylinder to solve this, anyway, the theory as to way is just that,
theory/speculation.<BR><BR>Hope this helps<BR><BR>Bob</FONT>
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