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murphy-rebel@dcsol.com at 18:34:58 on 30 Jun 2000.
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Walter, is the engine Zero'd or a used engine? If overhauled, CHT temps
usually run about 50 to 60 degrees hot until everything seats. Oil temp will
run about 20 or 30 degrees hot. I fly a minimum of 2 hours on an overhauled
engine in level flight at almost full power, with minor throttle changes
every 10 minutes or so. At about 1 hour 45 minutes I usually see the temps
suddenly drop to indicate that everything has seated in nice. Coming in any
sooner can glaze the cylinders and you will eat oil for ever.
If this is the case with you (zero'd engine) then maybe you just need to get
it back in the air and fly around until everything seats! Keep the nose down
to keep the air flow at max through the cowling on climb out! If not the
case and you have a previously broken in engine then yes open up the cowl
exit some more. Try the quick open up first. Then try the lip if necessary.
Angled lip will usually help drop the temps a few degrees, but also causes
drag.
Your temps on climb out are similar to what Howard experienced with his
during the first few flights. ie: about 500 F on Cylinders and 235/245 on
oil. These are not outside the Lycoming operating temperature range, but are
definitely on the high end. I ran 235 to 245 F oil temperature for 4 years
on my oil cooler less O-235-C with no detrimental effects, but this IS a
little high. Just don't open things up too much and drop the oil temp down
below 195/200 or you won't get the moisture out of the engine oil and the
motor will corrode.
One other thing! Is your propellor pitch allowing the engine to wind up to
full engine rated R.P.M in level flight with full throttle (or slightly
redline)? If you are not getting full R.P.M. then you are lugging your
engine and this will really cause the temps to rise. It's like pulling a
trailer up a step grade in high gear!!!
Hope there was some help in there!
Wayne G. O'Shea
www.irishfield.on.ca
-----Original Message-----
From: Walter Klatt <
Walter.Klatt@home.com>
To: (Murphy Rebel Builders List) <
murphy-rebel@dcsol.com>
Date: Friday, June 30, 2000 10:01 PM
Subject: Re: Another Rebel flys
My hottest CHT was cyl #3 and it would go right up to 500 at full power
in climb. Backing off to cruise power brought it down to about 450
degrees. Yes, very hot, so I only stayed up for about 1/2 hour for the
first flight. I will say that I was quite anxious there for awhile as I
watched that gauge climb straight up after the first take off.
The oil temp got up to about 235 degrees. My oil cooler is mounted at
the back of cyl #3, which explains why it was hotter than #4.
I have a weird old conical mount O320 with the carb at the back of the
oil pan, so my cut-out extends to the underside of the carb heat box. In
fact, the carb heat box probably helps block some of the airflow.
I had my opening cut out to about 100 square inches, and am planning to
increase it to about 126 with 1 inch lips for my next try. I can grind
the lips back later if the cooling is more than adequate.
Anyway, that's my current plan. Any other thoughts? Thanks.
"Wayne G. O'Shea" wrote:
CONGRATULATIONS WALT! Another great accomplishment in life licked!
As for your temperature problem, you didn't state CHT or Oil Temp. On
Howard's speed cowl we played with it for months, as he wanted to keep
that
stupid "out" take scoop under the carb area! We enlarged his about 3 fold
and then he put some exit scoops below his forward exhaust stacks also.
All
temperatures okay now, but a lot of extra work to accomplish!
When I did C-FXWI with the speed cowling I cut the bottom out in a
"circle"
from exhaust to exhaust pipe, with the arc coming forward to about an
inch
behind the dump pipe below the carb heat box. (If you meet up with the
Ramblers in B.C. you can have a look as Bob P. now owns and is flying it
on
the Ramble) This set up has worked great, without having to do any
fiberglass work building drag inducing lips etc.. Cylinder temps run at
about 375 F and oil about 205/210 F. Some have also incorporated cowl
flaps
to make up for difference between winter and summer, but shock cooling is
not usually a great problem on O-320 Lycomings as compared to the O-470's
and IO-520 Continentals in C180 and C185's .
Happy flying,
Wayne G. O'Shea
www.irishfield.on.ca
-----Original Message-----
From: Walter Klatt <
Walter.Klatt@home.com>
To: (Murphy Rebel) <
murphy-rebel@dcsol.com>
Date: Friday, June 30, 2000 9:55 AM
Subject: Another Rebel flys
Finally got 107R airborne on Monday June 26, 2000 at 7:45 PM. The plane
itself flew great, and it doesn't appear to need any adjustments to any
flight controls. My engine, however, was running a little on the hot
side. I am using the 150 HP O320 with a 3 blade Warp drive prop. I also
picked the hottest day of the year so far to test fly it, as we hit 32
degress C that day here in Langley B.C. In any case, though, I need to
enlarge the cowling opening at the bottom a little more to provide more
airflow. I'm wondering if any builders can give me some specific advice
here, in terms of size of opening, etc. I am using the Murphy speed
cowl. I have also noticed that some people build a lip on the bottom
opening to draw out more air. I didn't do that. Any comments or advice
would be appreciated. THX.
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