After forty years of modeling, I have stripped out my first set of glow plug threads. It happened to my OS .91 which is so old that it is questionable if it is worth fixing. Is anyone currently repairing this kind of damage? I checked back through my books. There were ads from 1990 for a company in California that could do the repair. I have also heard that Clarence Lee could install Helicoils. Does anyone have any ideas? Thanks Phil

Clarence Lee does install Helicoils. His ad is in the classified section of RCM and the price is good.

Paul

On the cheap (and better than Helicoil) Drill out the stripped hole and retap to 3/8" (assuming a 1/4" plug shank. Always go 2 sizes larger than the thread diameter), square off the tapered end of a grade 2-3 bolt and screw it in until flush with tthe combustion chamber, mark the depth and cut the bolt to length. Drill & tap the sleeve you've created to the plug thread and use the plug to drive the sleeve to the proper depth with your plug wrench. You then need to get and use the LockTite formula made for ASSEMBLED PARTS. The stuff I have is very thin and green in color. It will wick in and make the sleeve permanent. It will also make your plug permanent if you aren't careful to keep it out of the plug threads [] . A fine thread sleeve will grip better than a coarse thread, but a lot depends on what kind of bolts the local hardware carries... Afterward, you can also stake in the sleeve if it makes you feel better. If you have a large bolt supply house in your area, you might also be able to find some EZY-LOC inserts, which are basically the same things, but pre-made.

Thanks for the information. Phil Cope

If you are going the thread insert route check what is available. The last tme I used 'Helicoils" a special tap was needed. The is a similar product, it may be EZY-LOC that uses standard taps.

Ed S

The problem is finding an insert with the 1/4-32 thread.

Bill.

just send me the motor hee hee

After some searching, I have decided to follow SST's advice. The inserts like EZ-loc were not advertised in the 1/4-32 size. I was able to get the tap for the glow plug thread, not in stock, but available. His advise on the 3/8NF soft bolt and locktite is also good information. I hope this doesn't happen again, but it can be corrected. Thanks Phil