Glow-plug problems

[eppy]

Help,

Does anyone know what could be the cause of my glow plugs issues.
Some sort of black stuff slowly building on the wire in the glowplug over a period of maybe 10 - 12 tanks.
The plug in the attached pictures is the worst one so far, and made the engine cut forcing me to do my first auto :wow2:
( Time spent in the sim saves the day )

T-Rex 600 Nitro Pro
OS Hyper 50
Wildcat 15%
Just easy pattern flying in Normal Mode ( GV-1 @ 1700rpm )
I'm flying in a hot and humid climate.
I can easily hold my fingers on the backplate for more than 5 seconds.
About 7 gallons in total.

Fellow flyers at the field suggested opening the backplate and look for contamination, but it was very clean.

[JimLerch]

I've seen that once on my bird, but only about half as much as in your picture. I found I was running too rich, and the motor was not getting hot enough... Since I've started running it a leaner, I haven't had that problem.

[Mentalic]

Never seen a plug look like that, mine are always bright and shiny then over a long period of time begin to time look sandblasted.
I'd guess its something in the fuel, looks like gummy carbon. Maybe your plug is too cold? What type of plug are you running?

[eppy]

The plug is an O.S #8

[Mentalic]

Os #8's are not cold, so I'm going with its the fuel if your not running too rich. Thats not very many flights for that kind of buildup.

[WayneBrown]

the engine is not tuned to ideal conditions, and its not running in the optimum RPM range.
Have someone with more time help you tune it, with the governor OFF. You should see a reduced carbon deposit afterwards. Re-engage governor and fly.

[eppy]

Thanks for the input guys. Suspect I should get it off the gov and RTFM.
The adjustment section in the engines maual seems to be a good place to start.