Re: AD-10 photos

[drifter]

The engines was "gimme" along with a tank and two air cooled engines. All three were a mess (they were gimmies). Decided to make a "working" engine – one that I would use on a regular basis rather than a restoration – from the mess. Did a reseal of the L/U. Cleaned up the magneto and the carb. Compression was 75# and even. So far got $20 in it. Yeah, I painted it red because it was going to be a regular user as I live only 2 minutes from the ramp. And it would – no doubt – get banged around a little.
Started right up and ran pretty well, except for an irregular miss. Put a thermometer on the head and the lower cylinder was 30 degrees cooler. Led me to pull plugs and immediately notice the super clean lower plug along with the whitish goo in the cylinder. Pulled the power head and saw the goo that you see in the photo (I’ve since learned how to properly post a photo). Pulled the exhaust cover and found the hole (albeit, it is a very small hole).
So, I’ve got a plate and gasket on the way. The gasket surfaces look excellent and no warping. I removed the head to check the gasket and surfaces and found nothing wrong.
The 1/2" screw in plug was noticed early on and left alone. After the initial run and search for a cause of the water, I did remove the plug. The cavity does not lead into the water jacket, rather it leads into the crank case. It was a ham handed attempt by some PO to fill that cavity for some unknown reason. I have now replaced it with JB Weld. It was very difficult to remove and I was not about to spend time trying to re-thread it back into the hole since it was originally threaded very crooked. So, I ground down the bolt threads and placed it in the hole so it is less protrusive.
So, my thinking is that the hole in the plate has to be the culprit for the water in only lower cylinder.