Re: magneto misfiring

[m51rs]

'Our Ranger c-5 Fairchild had the following problem:

Installed overhauled magneto's. Engine ran perfect. After 40 minutes in the third flight of the day both started to misfire. Got worse by the minute.
Switching to one magneto did not help, even made things worse.

All temps were normal.

Somebody any ideas where to start looking? Magneto's, wiring, switch?

Thanks for your input.

Remko'

[Jim higham]

'Look for a stuck valve, do a compression check

-----Original Message-----
From: m51rs
Sent: Wednesday, May 26, 2010 2:23 PM
To: fairchildclub@yahoogroups.com
Subject: [fairchildclub] magneto misfiring


Our Ranger c-5 Fairchild had the following problem:

Installed overhauled magneto's. Engine ran perfect. After 40 minutes in the third flight of the day both started to misfire. Got worse by the minute.
Switching to one magneto did not help, even made things worse.

All temps were normal.

Somebody any ideas where to start looking? Magneto's, wiring, switch?

Thanks for your input.

Remko


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[Bob Webster]

'I had one go bad from a bad condenser. Doubtful if both would go bad at the same time though.

They are pretty easy to check generally with an analog VOM.

Bob

----- Original Message -----
From: m51rs
To: fairchildclub@yahoogroups.com
Sent: Wednesday, May 26, 2010 2:23 PM
Subject: [fairchildclub] magneto misfiring



Our Ranger c-5 Fairchild had the following problem:

Installed overhauled magneto's. Engine ran perfect. After 40 minutes in the third flight of the day both started to misfire. Got worse by the minute.
Switching to one magneto did not help, even made things worse.

All temps were normal.

Somebody any ideas where to start looking? Magneto's, wiring, switch?

Thanks for your input.

Remko





[Non-text portions of this message have been removed]

'

[Airy Millet]

'if both mags were overhauled with same components check them...



first look at contacts (if burnt or not), and their springs, and change one condenser on one side...



if still misfiring, look at harness (especially what I call "cigarettes", at the end, and springs making contact with spark plugs).



otherwise as already said, it may not come from ignition, but a stuck valve, or broken valve-spring (never encounter such problem, but...).



Airy



To: fairchildclub@yahoogroups.com
From: m51rs@yahoo.com
Date: Wed, 26 May 2010 19:23:46 +0000
Subject: [fairchildclub] magneto misfiring





Our Ranger c-5 Fairchild had the following problem:

Installed overhauled magneto's. Engine ran perfect. After 40 minutes in the third flight of the day both started to misfire. Got worse by the minute.
Switching to one magneto did not help, even made things worse.

All temps were normal.

Somebody any ideas where to start looking? Magneto's, wiring, switch?

Thanks for your input.

Remko





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[Tom_Downey]

'Remove both "P" leads and run it, see if it does the same thing in 40 minutes.

--- In fairchildclub@yahoogroups.com, "m51rs" wrote:
>
> Our Ranger c-5 Fairchild had the following problem:
>
> Installed overhauled magneto's. Engine ran perfect. After 40 minutes in the third flight of the day both started to misfire. Got worse by the minute.
> Switching to one magneto did not help, even made things worse.
>
> All temps were normal.
>
> Somebody any ideas where to start looking? Magneto's, wiring, switch?
>
> Thanks for your input.
>
> Remko
>

'

[Michael Denest]

'Remko,
6-440-C5 mags are timed at 25 degrees BTDC so the magneto installation should be reviewed.  Remove the covers over the points and check that there's a .012 to .015 gap. If not, adjust.  While you are at it, lube the felt oil strip with a thin viscosity oil.  Get number 1 cylinder to 25 degrees BTDC on the compression stroke.  Check the white markers in the mag windows to see if they are aligned.  If not, retime the mags.  Do the right one first as it is easier to do (no impulse coupling).  Once that one is done, do the left one.  Remember that the points opening is delayed by the impulse coupling.  You must make sure that it has snapped over before checking the timing.  I use a buzz box and a TimeRite gage to do this.  Takes me about a 1/2 hour to time both mags.  It will take a little longer with a timing wheel on the prop.

My bet is that both mags are improperly timed.    
 Mike


"He's crazy Lew, he builds toy airplanes".
- Capt. Frank Towns
Flight of the Phoenix



From: Tom_Downey
To: fairchildclub@yahoogroups.com
Sent: Wed, May 26, 2010 10:44:53 PM
Subject: [fairchildclub] Re: magneto misfiring

 
Remove both "P" leads and run it, see if it does the same thing in 40 minutes.

--- In fairchildclub@yahoogroups.com, "m51rs" wrote:
>
> Our Ranger c-5 Fairchild had the following problem:
>
> Installed overhauled magneto's. Engine ran perfect. After 40 minutes in the third flight of the day both started to misfire. Got worse by the minute.
> Switching to one magneto did not help, even made things worse.
>
> All temps were normal.
>
> Somebody any ideas where to start looking? Magneto's, wiring, switch?
>
> Thanks for your input.
>
> Remko
>







[Non-text portions of this message have been removed]

'

[Jim higham]

'Remko,
What did you ever figure out for your magneto troubles?
Jim
F24R46-108

-----Original Message-----
From: m51rs
Sent: Wednesday, May 26, 2010 2:23 PM
To: fairchildclub@yahoogroups.com
Subject: [fairchildclub] magneto misfiring


Our Ranger c-5 Fairchild had the following problem:

Installed overhauled magneto's. Engine ran perfect. After 40 minutes in the third flight of the day both started to misfire. Got worse by the minute.
Switching to one magneto did not help, even made things worse.

All temps were normal.

Somebody any ideas where to start looking? Magneto's, wiring, switch?

Thanks for your input.

Remko


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