FILENAMES: SparkPlug01.jpg SparkPlug02.jpg SparkPlug03.jpg SparkPlug04.jpg DESCRIPTION: These are pictures of repairing a stripped spark plug hole. Posted by Wayne Cook . The following description was provided: ================================================================= These are some pictures of my tractor when I fixed a stripped spark plug. The story of my original problems removing the plugs was posted in sci.eng.joining.welding so I won't repeat it here. The first shot shows the heads and propane tank. The plug I had to redo was #3. The second shot shows the hole after I drilled and tapped it to 7/8" x 14 tpi. I chose this size because I had a tap and it was just big enough to make the threaded bushing without cutting through. The third shot shows the plug with the bushing part way on it. I made the bushing because it was to expensive to buy the Helicoil set for 18mm plugs. The only set that MSC shows includes 24 bushings which would of been more than a lifetime supply for me. I've got a set for the more common 14mm plugs but the parts store doesn't carry the small set like that for the 18mm threads. I've used bushings similar to this in the past on motorcycles. There's no locking method but the flange at the top prevents it from screwing in to far. I used high temp loctite retaining compound on the bushing and only time will tell if it gets to hot. At anyrate it'll work whether the loctite holds or not but the bushing might come out with the plug next time. I did use antiseize on the plug threads to try and help the next time the plugs need changed. The fourth shot is a overall view of the tractor including the post hole digger I made for it. The digger will drill a 12" hole 5' deep if I need it. I made it after having to fix a borrowed digger because my uncle (the owner) had used hard bolts for the shear pin. After repairing the gear box I learned that even the heavy duty augers sold now days aren't heavy enough for rocky soil. This one is made from a real old (I think 30's-40's) truck differential. It's got a 5.30 - 1 ratio so the auger runs real slow. It's probably 10 times heavier than even a heavy duty commercial gear box. The strange object to the right of the tractor is a old single cylinder water cooled air compressor. The radiator is a old Fordson. I bought it at the closing auction of my former employer. It was our everyday compressor there for years (till they brought home a nice 7.5 hp two stage unit from auction one day). I'm not sure what the HP is but I guess at about 7.5 from the size of the motor though it might be 10. The pole in the middle of the picture was the one they installed when I got 3 phase for the shop.