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1. 01:59 PM - Re: Ghost in the engine 2200A (Naftali Horowitz)
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| Subject: | Ghost in the engine 2200A |
Try the following:
1. Adjust the butterfly to be about 5 deg. unparallel at WOT. That will cre
ate a vortex that might equalize the mixture distribution.
2. Tilt the carb about 5 deg. with the prop rotation. That might help in eq
ualizing R & L cyl.
Good luck!
From: don.honabach@pcperfect.com
Subject: RE: JabiruEngine-List: Ghost in the engine 2200A
Bob=2C
I posted this on the other list as well for you=2C but I added a few more t
houghts this morning that might be helpful.
=85=85..
I would have sworn you bumped the intake house during the annual as it soun
ded like turbulent air going into the carb which would have also made sense
considering the random cylinders temps as the hose tends to flex and move
a bit each test/RPM setting as the engine vibrates and moves under differen
t loads/settings.
I didn't see anything in your message about fuel testing beyond electric fu
el pump on/off. Is it possible the mechanical fuel pump is bad/going bad (I
'm assuming the 2200 has a mechanical fuel pump as my 3300A does?) or there
is a restriction in your fuel lines (new filter? mini clog?). Might be wor
th it to setup a temporary gravity feed setup that goes direct to the carb
(and/or into the mechanical fuel pump) so you can bypass fuel line related
issues. The roughness at higher RPMs for me has always been air related=2C
but lack of fuel I would think would cause the same symptoms you=92ve descr
ibed.
By the way=2C you mentioned that the one of the cylinders starts to cool do
wn when running rough=2C while I=92m not an expert by any means=2C this wou
ld seem to indicate that you are running rich at higher RPMs which makes me
wonder even more about the fuel pump/fuel hose setup going into the carb.
The cylinder that cools down is the one that just happens to get the most f
uel which will tend to change based on the air intake flows. This also seem
s to jive with your comments as most carbs are a bit unbalanced and favor e
ither the left or right bank of cylinders which will get just a tad bit mor
e air =85 which seems to align with your 2/4 being the usual culprits.
You might also want to check the air/fuel manifold if that is the correct t
erm for it ' I haven=92t looked closely at this area=2C but any small lea
ks might be okay at lower RPMs=2C but at higher RPMs could cause these same
sort of troubles.
I=92m assuming you re-tighten the head screws on the cylinders during the a
nnual ' did you have any noticeable issues there? Are you 100% sure that
all the head bolts are 100% at the specified torque values ' you got the
middle =91hidden=92 screw as well?
Good luck and please share when you find out the cause.
Don Honabach
P.S. When you tested with the scat house disconnected from the carb=2C did
you also remove the air sense tube on the carb as well? If not=2C you defin
itely will want to re-do that test with the air sense tube and scat disconn
ected. When troubleshooting my roughness at high RPM=2C I actually flew thi
s way (carb totally open to cowling) and quickly determined that my issue w
as turbulent air in the intake which took a ton of little tweaks to smooth
out. Also=2C did you plug up the air-intake on your cowling when doing the
test. If not=2C you may have had pressured type air shooting into the cowli
ng during the test (even during ground testing) and if it was anywhere near
the carb it would have messed things up for you at higher RPMs as the Bing
carb needs smooth air to function properly at high RPMs.
From: owner-jabiruengine-list-server@matronics.com [mailto:owner-jabiruengi
ne-list-server@matronics.com] On Behalf Of Bob Miller
Sent: Thursday=2C August 19=2C 2010 5:56 AM
Subject: JabiruEngine-List: Ghost in the engine 2200A
Hi Y'all=2C
I've got an engine problem that has all the experts stumped=2C including th
ose at US Jabiru. I'm grounded and heartbroken=2C and short of calling Cl
ick and Clack and playing Stump the Chump=2C don't know what to do. So if
you can solve this=2C you'll earn my undying appreciation (which=2C plus a
nickel=2C will get you....)
Here's a review of the situation so far.
The Problem:
Immediately after the annual inspection in March=2C the engine began runnin
g rough above about 2=2C650 rpm. It starts with a little roughness=2C and
the longer it runs above that rpm the rougher it gets=2C and soon the rpm s
tarts bouncing around wildly within a range of about 2=2C500 to 2=2C750. O
ne of the cylinders will start cooling down in EGTs and CHTs. Which cylind
er it is will change=3B it=92s nearly always 2 or 4=2C sometimes 3=2C and r
arely 1. When the power is reduced below about 2=2C650=2C the cool cylind
er warms up and everything runs smoothly.
It seems like after every change=2C it runs a little bit better for a littl
e while=2C but then reverts to the same problem. It=92s interesting that I
can run it for a while and have the problem be on one cylinder=2C then shut
it down for 5 minutes and then start it again and have the problem be on a
nother cylinder.
The following have resulted in no change:
L=2C R=2C or Both magnetos.
Carb heat On or Off.
Electric fuel pump On or Off.
Replaced rotors=2C distributor cap=2C spark plug wires=2C and sparkplugs.
New carburetor. (The only difference this made was that a couple EGTs ran
too high.)
Inspections that were normal:
I=92ve removed the carb and looked into the intake manifold but could see n
o obstructions or abnormalities.
There was no metal in the oil filter.
All the valve springs appear to have the same resistance when I push on the
m. The rocker arms all appear perfectly aligned when in the full up/out p
osition. (since the problem bounces from cylinder to cylinder=2C valve seem
s unlikely..?)
I also removed the air intake Scat hose and tried running it with carb inta
ke open to the engine compartment (with both the old and new carb).
--
Bob Miller
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