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  #1  
Old 12-10-2017, 04:45 PM
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chrispratt chrispratt is offline
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Default FOULED PLUG and IT PAYS TO LOOK AROUND ANTIME THE COWLING IS OFF

If you’ve never seen a fouled spark plug, this is an example of what one looks like. Note on the right side of the photo the bridged gap between anode and cathode effectively shorting out the plug. On mag check during run-up there was a drop of about 300 rpm followed by a backfire. This is an REM38E used on a standard magneto system and carbureted O-360-A1A. You can also see some carbon buildup on the plug walls in the background. I guess I need to floss my plugs more often Ya think I need to lean a bit more? Sure ruined my plans for the day.

BTW the plug had about 230 hours on it so it was just about due to be changed anyway along with the other 7 (I change my plugs at 250 hours).



On the positive side, while changing the plug I also discovered one of the connecting wires from my Unison Shower of Sparks was not in original condition (see below). Don’t know how this gap between connector and shielding happened; looks like I must have snagged it at some point and put a strain on the wire. A new Faston connector was soon substituted.

That’s why it pays to look around anytime the cowling is off.



Chris
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Last edited by chrispratt : 12-10-2017 at 07:29 PM.
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Old 12-10-2017, 07:32 PM
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Default

Looks to me like some kind of automotive wire was used and the insulation shrunk back. Rip it out and start over
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Old 12-10-2017, 08:20 PM
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That may be, Walt. That's the wire that came with the original unit and being a rookie builder at the time (about 14 years ago) I used what the OEM sent. I replaced it with Tefzel wire.
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  #4  
Old 12-11-2017, 06:00 AM
fixnflyguy fixnflyguy is offline
 
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Default Happened to me too..

Same thing just happened to me last week, but I had a cracked insulator that made it even worse. I was accused of "making Popcorn" during run-up the popping was so loud! Same exact plug type.
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Old 12-11-2017, 06:31 AM
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I love my fine-wires!
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Old 12-11-2017, 07:10 AM
6 Gun 6 Gun is offline
 
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Smile Plugs

I have ran NGK auto plugs for last 100 hours on one of my slick mags gapped at out of the box .025 has worked very well and cost $2.30 each don't know how to post pics but if anyone wants to know how I converted wire to auto send me a PM.
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Old 12-11-2017, 08:20 AM
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Exclamation

That sort of fouling is good reason to change to the REM37BY plugs with extended tips -



Should be good and approved in all of our engines, but you can check here -

https://www.lycoming.com/sites/defau...rk%20Plugs.pdf
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  #8  
Old 12-11-2017, 08:30 AM
blastinbill blastinbill is offline
 
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Default Fouled Plugs

I have had trouble with lead-fouled REM-38E massive plugs in both the previous Lycoming O-360A1A in my Piper Comanche and in the present engine until I switched to 4 Tempest fine wires on the bottom and REM-37BY's on the top about two years ago. No problem since, and I can go lean of peak until misfire occurs a lot farther than before.
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Old 12-11-2017, 08:36 AM
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Bob Martin Bob Martin is offline
 
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Default Mags

Quote:
Originally Posted by 6 Gun View Post
I have ran NGK auto plugs for last 100 hours on one of my slick mags gapped at out of the box .025 has worked very well and cost $2.30 each don't know how to post pics but if anyone wants to know how I converted wire to auto send me a PM.
I was under the impression the Sparkplug gap was determined by the source of the ignition and the mags were designed for 18 to 20..?
A bigger gap is taxing the coils/etc and will eventually lead to failure.
Food for thought.
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  #10  
Old 12-11-2017, 09:21 AM
DNeufeld DNeufeld is offline
 
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Default

Quote:
Originally Posted by Bob Martin View Post
I was under the impression the Sparkplug gap was determined by the source of the ignition and the mags were designed for 18 to 20..?
A bigger gap is taxing the coils/etc and will eventually lead to failure.
Food for thought.
Yep, me too.
The higher the secondary voltage, coil, plugs and plug wires, the higher the primary voltage, points, condenser, coil. High voltage is always looking for an easier path to ground. Also burns points...
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