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1. 06:21 PM - Re: Uneven EGTs at full throttle (Bill Strahan)
2. 11:25 PM - Re: Re: Uneven EGTs at full throttle (James, Clive R)
Message 1
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| Subject: | Re: Uneven EGTs at full throttle |
Quick update on the radiator hose experiment. I got it trimmed and installed,
and it looked like a perfectly smooth 90 degree bend. Ran it on the ground, everything
was great, so a re-cowled it and test flew it.
I was quite surprised. There's a lot going on during takeoff, with vibration from
the engine as well as the rolling tires, so it was only after I was airborne
that I realized the engine was vibrating pretty hard.
I throttled back slowly, and after pulling the throttle back about 1/2 inch the
vibration ceased and the RPMs increaed!
I left it there during climbout, and after reaching a safe altitude I firewalled
it again. Immediate vibration, and drop in EGT on cylinders 2,4,6. In fact,
I was getting higher RPMs with lower fuel flow when it wasn't firewalled.
So, I don't know what to conclude exactly. Throttled back 1/2-3/4" the engine
runs smooth as silk now that I've balanced the prop. The EGTs all line up within
about 30 degrees of each other. But the closer to firewalled it gets the
worse it runs.
At this point, I can conclude that the full throttle problem is not related to
the swirl from the SCAT tubing. That's not to say it isn't related to the 90
degree bend that close to the carburetor, but it seems unlikely. The problem
is actually worse now, since the engine didn't run this rough with the SCAT tubing.
Not sure what to try next, but I'll make a posting if I have a breakthrough.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=272988#272988
Message 2
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| Subject: | Re: Uneven EGTs at full throttle |
Bill, this is the same as my Esqual though when loaded (lower RPM on
roll and climb out) it's not so noticeable it seems to come in as rpm
increases.
Something on my to do list when I get the 'other issues' sorted.
Since I last flew the plane (January 09), I've fitted a smooth bend (GM
engined Vectra from breakers yard) though I didn't expect it to fix
this, just something that has been an improvement for others..
I was more thinking it was about the mixture when off the needle jet and
onto the main jet.
So, thanks for update, I await your next bulletin with interest.
Regards, Clive
Esqual in UK (+ Jab SP)
-----Original Message-----
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of Bill
Strahan
Sent: 16 November 2009 02:21
Subject: Lightning-List: Re: Uneven EGTs at full throttle
Quick update on the radiator hose experiment. I got it trimmed and
installed, and it looked like a perfectly smooth 90 degree bend. Ran it
on the ground, everything was great, so a re-cowled it and test flew it.
I was quite surprised. There's a lot going on during takeoff, with
vibration from the engine as well as the rolling tires, so it was only
after I was airborne that I realized the engine was vibrating pretty
hard.
I throttled back slowly, and after pulling the throttle back about 1/2
inch the vibration ceased and the RPMs increaed!
I left it there during climbout, and after reaching a safe altitude I
firewalled it again. Immediate vibration, and drop in EGT on cylinders
2,4,6. In fact, I was getting higher RPMs with lower fuel flow when it
wasn't firewalled.
So, I don't know what to conclude exactly. Throttled back 1/2-3/4" the
engine runs smooth as silk now that I've balanced the prop. The EGTs
all line up within about 30 degrees of each other. But the closer to
firewalled it gets the worse it runs.
At this point, I can conclude that the full throttle problem is not
related to the swirl from the SCAT tubing. That's not to say it isn't
related to the 90 degree bend that close to the carburetor, but it seems
unlikely. The problem is actually worse now, since the engine didn't
run this rough with the SCAT tubing.
Not sure what to try next, but I'll make a posting if I have a
breakthrough.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=272988#272988
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