Soft RCGF (Original) Threads...

One of the few problems with the original version RCGF 10cc engine is the soft threading of the spark plug site at the top of the cylinder  (this engine is now "obsolete", and this is not a problem with RCGF-USA 10cc Stinger engines).  As of today I have stripped 3 of these in 9 years. Today was removing a spark plug wire from one of the oldest engines I have, probably 9 yrs old now, and the whole sparky came out still attached to the ignition plug adapter, stripped clean from the cylinder! 

All excited, the replacement muffler arrived from Joe Nelson at RCGF-USA! 

A little JB Weld gasketing and done!

Engine looks good, finished trim of the cowl for a nice fit (not shown).

All ready for testing. I noticed some fraying of the shrink wrap around the plug adapter so turned her over and pulled the plug. Resisted a bit then came out. ALL of it, sparky and all!

Clean stripped the cylinder head spark plug opening! The past two times I did this I "over tightened" the plug, so I've learned to have a soft touch.

Tried to re--tap it...

But there just wasn't enough left...

Just a peak at the inside holding the plug in, for giggles. I had wiped some of the carbon build up out, will give it a nice clean with some steel wool. I need a fix, surely this might happen again with the old cylinder heads.

So, instead of buying another cylinder head for $56, I decided to try this nifty adapter thingy! This is a 10mm-to-1/4 32 spark plug adapter from CH Ignitions, made of steel. I found myself thinking once again if anyone had a fix for this sort of thing. Surely this is not a unique problem. I hadn't searched for the right thing in the past, but today wondered if there was an adapter, and voila! So that's on its way, through eBay. Challenges remain: I have a 1.5 and a 1.75 modulus 10mm tap, not sure which this is, but have an inquiry in. Now this is really designed for a 10mm opening to allow a smaller spark, like down from a CM6 to a 1/4-32, not so much a retapped hole, so we'll see.

I will be pulling this motor and setting it aside. Joe has sent me a replacement engine for the Stik's RCGF 10cc, also about 9 years old. I did a number on it and he called it "kaput". Once that's in we can get this engine tested and get her up in the air! Hopefully that will be here in the next few days!