The Murphy Builders Site

When you say "at altittude"..how high we talkin? Bob P found out that his/my
freshly overhauled, by Leavens, engine/mags had cracked coils that only
misfired when he was way up there.

----- Original Message -----
From: "michael betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 10:31 AM
Subject: [rebel-builders] Engine miss?

Hi,
I have about 30 hours on my Elite with an 0360 in it. I'm not sure if
this problem is been from the start or at least somewhere around 10
hours into it. Under full power no problem, but at altitude I pull back
to 2400 or 2500 and the engine will give a quick jerk every couple
seconds. If I pull back to 2400 or less the problem goes away. If I go
full throttle, it goes away too. It also isn't very consistent either,
some days worse than others. My passengers don't notice it either
unless I tell them about it. I recently pulled the plugs and they are
text book color and clean. I tried turning off mags in flight and it
almost seems like the twitch is there in either position. I get about
75 rpm drops on both mags during run up. The air filter is K&N, I can't
imagine that being an issue already. The local A&P's find it odd to
only occur during small range of rpm.
Any ideas or experience of this?
Mike Betti
771E



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It does it at pattern here, 2000 msl as it does at any other altitude, when
I stop my climb and power back is the main factor. About a 200 rpm window.
Get out of that range and all fine. I haven't tried running it there
continuously to see if it persist, less than a minute and I am adjusting
throttle. This is a simiular thing I might experience when leaning too.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 9:41 AM
Subject: Re: [rebel-builders] Engine miss?

When you say "at altittude"..how high we talkin? Bob P found out that
his/my
freshly overhauled, by Leavens, engine/mags had cracked coils that only
misfired when he was way up there.

----- Original Message -----
From: "michael betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 10:31 AM
Subject: [rebel-builders] Engine miss?

Hi,
I have about 30 hours on my Elite with an 0360 in it. I'm not sure if
this problem is been from the start or at least somewhere around 10
hours into it. Under full power no problem, but at altitude I pull back
to 2400 or 2500 and the engine will give a quick jerk every couple
seconds. If I pull back to 2400 or less the problem goes away. If I go
full throttle, it goes away too. It also isn't very consistent either,
some days worse than others. My passengers don't notice it either
unless I tell them about it. I recently pulled the plugs and they are
text book color and clean. I tried turning off mags in flight and it
almost seems like the twitch is there in either position. I get about
75 rpm drops on both mags during run up. The air filter is K&N, I can't
imagine that being an issue already. The local A&P's find it odd to
only occur during small range of rpm.
Any ideas or experience of this?
Mike Betti
771E



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Sounds similar to a problem Walter had. Are your primer lines flared and do
you have a male and female cap...that you can take the line off the primer
outlet and cap both it and the line...then go play again.

People told me I was nuts with that diagnosis on Walters bird...but Walter
didn't !

----- Original Message -----
From: "Mike Betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 3:08 PM
Subject: Re: [rebel-builders] Engine miss?

It does it at pattern here, 2000 msl as it does at any other altitude,
when
I stop my climb and power back is the main factor. About a 200 rpm window.
Get out of that range and all fine. I haven't tried running it there
continuously to see if it persist, less than a minute and I am adjusting
throttle. This is a simiular thing I might experience when leaning too.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 9:41 AM
Subject: Re: [rebel-builders] Engine miss?

When you say "at altittude"..how high we talkin? Bob P found out that
his/my
freshly overhauled, by Leavens, engine/mags had cracked coils that only
misfired when he was way up there.

----- Original Message -----
From: "michael betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 10:31 AM
Subject: [rebel-builders] Engine miss?

Hi,
I have about 30 hours on my Elite with an 0360 in it. I'm not sure if
this problem is been from the start or at least somewhere around 10
hours into it. Under full power no problem, but at altitude I pull back
to 2400 or 2500 and the engine will give a quick jerk every couple
seconds. If I pull back to 2400 or less the problem goes away. If I go
full throttle, it goes away too. It also isn't very consistent either,
some days worse than others. My passengers don't notice it either
unless I tell them about it. I recently pulled the plugs and they are
text book color and clean. I tried turning off mags in flight and it
almost seems like the twitch is there in either position. I get about
75 rpm drops on both mags during run up. The air filter is K&N, I can't
imagine that being an issue already. The local A&P's find it odd to
only occur during small range of rpm.
Any ideas or experience of this?
Mike Betti
771E



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Maybe wrong carb or jet?

From: "Mike Betti" <mbetti@hughes.net>
Reply-To: <rebel-builders@dcsol.com>
To: <rebel-builders@dcsol.com>
Subject: Re: [rebel-builders] Engine miss?
Date: Sun, 3 Jun 2007 14:08:45 -0500

It does it at pattern here, 2000 msl as it does at any other altitude, when
I stop my climb and power back is the main factor. About a 200 rpm window.
Get out of that range and all fine. I haven't tried running it there
continuously to see if it persist, less than a minute and I am adjusting
throttle. This is a simiular thing I might experience when leaning too.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 9:41 AM
Subject: Re: [rebel-builders] Engine miss?

When you say "at altittude"..how high we talkin? Bob P found out that
his/my
freshly overhauled, by Leavens, engine/mags had cracked coils that only
misfired when he was way up there.

----- Original Message -----
From: "michael betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 10:31 AM
Subject: [rebel-builders] Engine miss?

Hi,
I have about 30 hours on my Elite with an 0360 in it. I'm not sure if
this problem is been from the start or at least somewhere around 10
hours into it. Under full power no problem, but at altitude I pull back
to 2400 or 2500 and the engine will give a quick jerk every couple
seconds. If I pull back to 2400 or less the problem goes away. If I go
full throttle, it goes away too. It also isn't very consistent either,
some days worse than others. My passengers don't notice it either
unless I tell them about it. I recently pulled the plugs and they are
text book color and clean. I tried turning off mags in flight and it
almost seems like the twitch is there in either position. I get about
75 rpm drops on both mags during run up. The air filter is K&N, I can't
imagine that being an issue already. The local A&P's find it odd to
only occur during small range of rpm.
Any ideas or experience of this?
Mike Betti
771E



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Numbers match but I think I will do some more research on that topic.

----- Original Message -----
From: "Jesse Jenks" <jessejenks@hotmail.com>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 5:30 PM
Subject: Re: [rebel-builders] Engine miss?

Maybe wrong carb or jet?

From: "Mike Betti" <mbetti@hughes.net>
Reply-To: <rebel-builders@dcsol.com>
To: <rebel-builders@dcsol.com>
Subject: Re: [rebel-builders] Engine miss?
Date: Sun, 3 Jun 2007 14:08:45 -0500

It does it at pattern here, 2000 msl as it does at any other altitude,
when
I stop my climb and power back is the main factor. About a 200 rpm window.
Get out of that range and all fine. I haven't tried running it there
continuously to see if it persist, less than a minute and I am adjusting
throttle. This is a simiular thing I might experience when leaning too.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 9:41 AM
Subject: Re: [rebel-builders] Engine miss?

When you say "at altittude"..how high we talkin? Bob P found out that
his/my
freshly overhauled, by Leavens, engine/mags had cracked coils that only
misfired when he was way up there.

----- Original Message -----
From: "michael betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 10:31 AM
Subject: [rebel-builders] Engine miss?




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Like puzzles? Play free games & earn great prizes. Play Clink now.
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I think I have caps, I'll give it a try.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 2:17 PM
Subject: Re: [rebel-builders] Engine miss?

Sounds similar to a problem Walter had. Are your primer lines flared and
do
you have a male and female cap...that you can take the line off the primer
outlet and cap both it and the line...then go play again.

People told me I was nuts with that diagnosis on Walters bird...but Walter
didn't !

----- Original Message -----
From: "Mike Betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 3:08 PM
Subject: Re: [rebel-builders] Engine miss?

It does it at pattern here, 2000 msl as it does at any other altitude,
when
I stop my climb and power back is the main factor. About a 200 rpm
window.
Get out of that range and all fine. I haven't tried running it there
continuously to see if it persist, less than a minute and I am adjusting
throttle. This is a simiular thing I might experience when leaning too.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 9:41 AM
Subject: Re: [rebel-builders] Engine miss?

When you say "at altittude"..how high we talkin? Bob P found out that
his/my
freshly overhauled, by Leavens, engine/mags had cracked coils that only
misfired when he was way up there.

----- Original Message -----
From: "michael betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 10:31 AM
Subject: [rebel-builders] Engine miss?




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Yup, never ever did doubt Wayne's airframe or engine acumen, but he
impressed even me with that diagnosis, and from 2000 miles away.

Mike, just in case, check your primer to see if any dirt might be keeping it
from sealing off fuel when closed. I was surprised to learn that the primer
input line on my gascolator is not filtered. So I had a bunch of crap that
got sucked up into my primer over time which eventually caused the primer to
not seal properly when closed.

Just got back from the lake, from a very hot weekend. Temps have been over
30 here for several days. Water temps at my dock reached 70F today, and
needless to say, spent a lot of time in the water cooling off. It's supposed
to cool off tomorrow, and a good thing, or we could have been in for some
serious flooding, as there is still a lot of snow melt to come from the high
alpine.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Wayne
G. O'Shea
Sent: Sunday, June 03, 2007 12:18 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Engine miss?

Sounds similar to a problem Walter had. Are your primer lines flared and do
you have a male and female cap...that you can take the line off the primer
outlet and cap both it and the line...then go play again.

People told me I was nuts with that diagnosis on Walters bird...but Walter
didn't !

----- Original Message -----
From: "Mike Betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 3:08 PM
Subject: Re: [rebel-builders] Engine miss?

It does it at pattern here, 2000 msl as it does at any other altitude,
when
I stop my climb and power back is the main factor. About a 200 rpm window.
Get out of that range and all fine. I haven't tried running it there
continuously to see if it persist, less than a minute and I am adjusting
throttle. This is a simiular thing I might experience when leaning too.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 9:41 AM
Subject: Re: [rebel-builders] Engine miss?

When you say "at altittude"..how high we talkin? Bob P found out that
his/my
freshly overhauled, by Leavens, engine/mags had cracked coils that only
misfired when he was way up there.

----- Original Message -----
From: "michael betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 10:31 AM
Subject: [rebel-builders] Engine miss?

Hi,
I have about 30 hours on my Elite with an 0360 in it. I'm not sure if
this problem is been from the start or at least somewhere around 10
hours into it. Under full power no problem, but at altitude I pull back
to 2400 or 2500 and the engine will give a quick jerk every couple
seconds. If I pull back to 2400 or less the problem goes away. If I go
full throttle, it goes away too. It also isn't very consistent either,
some days worse than others. My passengers don't notice it either
unless I tell them about it. I recently pulled the plugs and they are
text book color and clean. I tried turning off mags in flight and it
almost seems like the twitch is there in either position. I get about
75 rpm drops on both mags during run up. The air filter is K&N, I can't
imagine that being an issue already. The local A&P's find it odd to
only occur during small range of rpm.
Any ideas or experience of this?
Mike Betti
771E



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Could the miss be the result of a vibration, such as second or third
harmonic? This is a stretch but could the carb be "buzzing" vibrating
and making foam and causing a fuel interruption, or something else in
the fuel system

Dick Wampach SR-108

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Mike Betti
Sent: Sunday, June 03, 2007 12:09 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Engine miss?

It does it at pattern here, 2000 msl as it does at any other altitude,
when
I stop my climb and power back is the main factor. About a 200 rpm
window.
Get out of that range and all fine. I haven't tried running it there
continuously to see if it persist, less than a minute and I am adjusting

throttle. This is a simiular thing I might experience when leaning too.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 9:41 AM
Subject: Re: [rebel-builders] Engine miss?

When you say "at altittude"..how high we talkin? Bob P found out that
his/my
freshly overhauled, by Leavens, engine/mags had cracked coils that

only

misfired when he was way up there.

----- Original Message -----
From: "michael betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 10:31 AM
Subject: [rebel-builders] Engine miss?

Hi,
I have about 30 hours on my Elite with an 0360 in it. I'm not sure if
this problem is been from the start or at least somewhere around 10
hours into it. Under full power no problem, but at altitude I pull

back

to 2400 or 2500 and the engine will give a quick jerk every couple
seconds. If I pull back to 2400 or less the problem goes away. If I

go

full throttle, it goes away too. It also isn't very consistent

either,

some days worse than others. My passengers don't notice it either
unless I tell them about it. I recently pulled the plugs and they are
text book color and clean. I tried turning off mags in flight and it
almost seems like the twitch is there in either position. I get about
75 rpm drops on both mags during run up. The air filter is K&N, I

can't

imagine that being an issue already. The local A&P's find it odd to
only occur during small range of rpm.
Any ideas or experience of this?
Mike Betti
771E



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That was exactly my thought, Richard ! Almost ALL combinations
of O-360's and metal props have SOME harmonic range where
continuous operation is prohibited ... usually in the 1,900 to
2,450 rpm area. Some are more, or less .... could be as small
as 2300 - 2450 on some.

Certainly, if it hits that harmonic, the prop, and/or
crankshaft can be flexing vigorously enough to get the
fuel frothing ......

A long time ago, I saw a video of the crankshaft in
harmonic flutter - it's pretty scarey !!!

--
......bobp
http://www.prosumers.ca
http://bpatterson.qhealthbeauty.com
http://apatterson2.qhealthzone.com

-------------------------------orig.-------------------------
On Monday 04 June 2007 02:21, Richard Wampach wrote:

Could the miss be the result of a vibration, such as second or third
harmonic? This is a stretch but could the carb be "buzzing" vibrating
and making foam and causing a fuel interruption, or something else in
the fuel system

Dick Wampach SR-108

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Mike Betti
Sent: Sunday, June 03, 2007 12:09 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Engine miss?

It does it at pattern here, 2000 msl as it does at any other altitude,
when
I stop my climb and power back is the main factor. About a 200 rpm
window.
Get out of that range and all fine. I haven't tried running it there
continuously to see if it persist, less than a minute and I am adjusting

throttle. This is a simiular thing I might experience when leaning too.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 9:41 AM
Subject: Re: [rebel-builders] Engine miss?

When you say "at altittude"..how high we talkin? Bob P found out that
his/my
freshly overhauled, by Leavens, engine/mags had cracked coils that

only

misfired when he was way up there.

----- Original Message -----
From: "michael betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 10:31 AM
Subject: [rebel-builders] Engine miss?

Hi,
I have about 30 hours on my Elite with an 0360 in it. I'm not sure if
this problem is been from the start or at least somewhere around 10
hours into it. Under full power no problem, but at altitude I pull

back

to 2400 or 2500 and the engine will give a quick jerk every couple
seconds. If I pull back to 2400 or less the problem goes away. If I

go

full throttle, it goes away too. It also isn't very consistent

either,

some days worse than others. My passengers don't notice it either
unless I tell them about it. I recently pulled the plugs and they are
text book color and clean. I tried turning off mags in flight and it
almost seems like the twitch is there in either position. I get about
75 rpm drops on both mags during run up. The air filter is K&N, I

can't

imagine that being an issue already. The local A&P's find it odd to
only occur during small range of rpm.
Any ideas or experience of this?
Mike Betti
771E

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I like your idea Wayne, may be a week before I get to try it. I find it
strange that I have to give several dry prime pumps before I get fuel to the
primer, and just after sitting overnight.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 2:17 PM
Subject: Re: [rebel-builders] Engine miss?

Sounds similar to a problem Walter had. Are your primer lines flared and
do
you have a male and female cap...that you can take the line off the primer
outlet and cap both it and the line...then go play again.

People told me I was nuts with that diagnosis on Walters bird...but Walter
didn't !

----- Original Message -----
From: "Mike Betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 3:08 PM
Subject: Re: [rebel-builders] Engine miss?

It does it at pattern here, 2000 msl as it does at any other altitude,
when
I stop my climb and power back is the main factor. About a 200 rpm
window.
Get out of that range and all fine. I haven't tried running it there
continuously to see if it persist, less than a minute and I am adjusting
throttle. This is a simiular thing I might experience when leaning too.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 9:41 AM
Subject: Re: [rebel-builders] Engine miss?

When you say "at altittude"..how high we talkin? Bob P found out that
his/my
freshly overhauled, by Leavens, engine/mags had cracked coils that only
misfired when he was way up there.

----- Original Message -----
From: "michael betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 10:31 AM
Subject: [rebel-builders] Engine miss?




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Sounds like you have a stuck check ball and you're thus sucking extra fuel
to the intake thru the primer at certain manifold pressures.

----- Original Message -----
From: "Mike Betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Monday, June 04, 2007 5:52 PM
Subject: Re: [rebel-builders] Engine miss?

I like your idea Wayne, may be a week before I get to try it. I find it
strange that I have to give several dry prime pumps before I get fuel to
the
primer, and just after sitting overnight.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 2:17 PM
Subject: Re: [rebel-builders] Engine miss?

Sounds similar to a problem Walter had. Are your primer lines flared and
do
you have a male and female cap...that you can take the line off the
primer
outlet and cap both it and the line...then go play again.

People told me I was nuts with that diagnosis on Walters bird...but
Walter
didn't !

----- Original Message -----
From: "Mike Betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 3:08 PM
Subject: Re: [rebel-builders] Engine miss?

It does it at pattern here, 2000 msl as it does at any other altitude,
when
I stop my climb and power back is the main factor. About a 200 rpm
window.
Get out of that range and all fine. I haven't tried running it there
continuously to see if it persist, less than a minute and I am adjusting
throttle. This is a simiular thing I might experience when leaning too.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 9:41 AM
Subject: Re: [rebel-builders] Engine miss?



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I hope your right Wayne, that's an easy fix.

The talk about engine harmonics by others, is there any way to know what rpm
to avoid or what not to do from an operators stand point with this setup?
Thanks,
Mike Betti

----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Monday, June 04, 2007 6:17 PM
Subject: Re: [rebel-builders] Engine miss?

Sounds like you have a stuck check ball and you're thus sucking extra fuel
to the intake thru the primer at certain manifold pressures.

----- Original Message -----
From: "Mike Betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Monday, June 04, 2007 5:52 PM
Subject: Re: [rebel-builders] Engine miss?

I like your idea Wayne, may be a week before I get to try it. I find it
strange that I have to give several dry prime pumps before I get fuel to
the
primer, and just after sitting overnight.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 2:17 PM
Subject: Re: [rebel-builders] Engine miss?

Sounds similar to a problem Walter had. Are your primer lines flared and
do
you have a male and female cap...that you can take the line off the
primer
outlet and cap both it and the line...then go play again.

People told me I was nuts with that diagnosis on Walters bird...but
Walter
didn't !

----- Original Message -----
From: "Mike Betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 3:08 PM
Subject: Re: [rebel-builders] Engine miss?




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Hi Mike !

I think the Lycoming web site has a section on the particular
engine and prop combinations and the "avoid continuous operation"
harmonic vibration ranges - they can run from 1,900 to 2,450 rpm.
Most O-360's are in the 2,100 - 2,450 area .... We run 4 of them
on Super Cub towplanes... Takes care to get proper cooling
and avoid the sensitive rpms.

--
......bobp
http://www.prosumers.ca
http://bpatterson.qhealthbeauty.com
http://apatterson2.qhealthzone.com

-------------------------------orig.-------------------------
On Tuesday 05 June 2007 00:21, Mike Betti wrote:

I hope your right Wayne, that's an easy fix.

The talk about engine harmonics by others, is there any way to know what
rpm to avoid or what not to do from an operators stand point with this
setup? Thanks,
Mike Betti

----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Monday, June 04, 2007 6:17 PM
Subject: Re: [rebel-builders] Engine miss?

Sounds like you have a stuck check ball and you're thus sucking extra
fuel to the intake thru the primer at certain manifold pressures.

----- Original Message -----
From: "Mike Betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Monday, June 04, 2007 5:52 PM
Subject: Re: [rebel-builders] Engine miss?

I like your idea Wayne, may be a week before I get to try it. I find it
strange that I have to give several dry prime pumps before I get fuel to
the
primer, and just after sitting overnight.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 2:17 PM
Subject: Re: [rebel-builders] Engine miss?

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The torsional harmonics that quickly break crankshafts like a opera
singer breaks wine glasses are not apparent to the operator until
something breaks. The testing is expensive and out of the question for
most homebuilder and is the reason for "approved" engine and prop
combinations on particular airframes. I think it is also one of the
reasons that lighter props and vibration absorbing wood props are
favoured by homebuilders. My own opinion is that you are fairly safe
moving an approved engine and prop to a different airframe but there is
no guarantee of that as sometimes a different cowl shape can excite a
prop and start things oscillating I'm told. Torsional vibrations twist
and untwist the crankshaft. Should you have a combination that resonates
at its natural frequency (think wine glass) at an operating rpm,
something such as crankshaft or prop is going to break. As has been
said, there are combinations that are approved under the proviso that
you avoid steady operation a certain problem engine speeds. You can not
feel these vibrations.

The harmonics that you can feel from side to side shaking are not near
as destructive and I'm not aware of any approved combinations that
specify engine speeds to avoid because of these. They might be
noticeable and annoying enough to cause you to avoid particular rpms
though. Some guys would likely recommend checking the prop balance
(engine running) as a first investigative step. That is a different
thing but still a good idea. Repeated engine mount cracks and such could
be due to these kinds of shaking. Vibration sensors of various types
will measure these kinds of vibrations but other than balancing the
prop, there is not much you can do about them.

So the answer is no. However an approved combination or a combination
that others have accumulated time on is a good bet. Avoiding operating
where the engine shakes more than normal is pretty obvious but it
guarantees nothing.

Sounds to me like there is a more basic mixture or ignition issue here.
I'll be interested in hearing how it plays out. Mixture imbalances are
usually only apparent after leaning but a leaking primer can be a huge
rich imbalance.

Ken


Mike Betti wrote:

I hope your right Wayne, that's an easy fix.

The talk about engine harmonics by others, is there any way to know what rpm
to avoid or what not to do from an operators stand point with this setup?
Thanks,
Mike Betti

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I removed the primer today and capped off both lines, same problem :(
The prop is cautioned for use at 2150-2350. 2400 and 2500 is my problem
area. My smoothest operation has been in the cautioned area. I can cruise at
2400 but I still get that little hickup every once in the while. It's not
enough to shake the plane but I can detect it with through my feet more than
anything, you have to pay attention to notice it. Feels electrical like one
plug missing a beat once in the while, but it does it on both mags. Not sure
if I want to pull the carb or try another set of plugs.
Mike Betti

----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 2:17 PM
Subject: Re: [rebel-builders] Engine miss?

Sounds similar to a problem Walter had. Are your primer lines flared and
do
you have a male and female cap...that you can take the line off the primer
outlet and cap both it and the line...then go play again.

People told me I was nuts with that diagnosis on Walters bird...but Walter
didn't !

----- Original Message -----
From: "Mike Betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 3:08 PM
Subject: Re: [rebel-builders] Engine miss?

It does it at pattern here, 2000 msl as it does at any other altitude,
when
I stop my climb and power back is the main factor. About a 200 rpm
window.
Get out of that range and all fine. I haven't tried running it there
continuously to see if it persist, less than a minute and I am adjusting
throttle. This is a simiular thing I might experience when leaning too.
Mike
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 9:41 AM
Subject: Re: [rebel-builders] Engine miss?

When you say "at altittude"..how high we talkin? Bob P found out that
his/my
freshly overhauled, by Leavens, engine/mags had cracked coils that only
misfired when he was way up there.

----- Original Message -----
From: "michael betti" <mbetti@hughes.net>
To: <rebel-builders@dcsol.com>
Sent: Sunday, June 03, 2007 10:31 AM
Subject: [rebel-builders] Engine miss?




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