RE: Thunder Tiger 130 Four Stroke
I take it back.I removed the engine from the plane to do a thorough check of its condition after the backfiring and plug eating antics. I noticed some scoring of the plug threads and some fluff.I reckon its because the threads were not deep enough and as a result of the glow plug "making" new threads further in, it caused some of the gunk to be embedded in the threads as the plug was screwed out.
Custom PC was right, the threads are not deep enough, its just that because of a combination of ham fistedness and threads that thankfully did not give way, i did not notice anything amiss. Thing is that you might get a leak if a compressed or thinner washer is used which actually alerted me to the problem as I could hear whistling noises as i turned the prop over. A fix is needed or you might get a stripped thread eventually or inconsistent runs.