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Glen, This has to do with the use of a shorter spark plug on top of the cylinders. The newer, typical plug and ignition harness wire attaches directly out of the top of a longer spark plug (this can be used on the bottom plugs). But if this is used on the top spark plugs, then the bumps are required to provide clearance with the wire and the cowling. But with the use of shorter plugs and a Ercoupe cup, the newer type screw-on harness wires are installed at more of a right angle to the plug. This gives the needed clearance without the cowling bumps. I've attached a couple of pictures showing the original cup parts and the newer Ercoupe-cup parts that I used on my plane. The only negative to the cups is that they have to be machined to fit the standard thread used on the ignition harness wire. They come with a larger thread diameter. but this is easily done with a lathe and correct die. It sure looks a lot cleaner without the cowling bumps. Richard McClure (N94004) <<MVC-025S.JPG>> <<MVC-022S.JPG>> <<MVC-013S.JPG>> ========================================================================== ==== To leave this forum go to: http://ercoupers.com/lists.htm Search the archives on http://escribe.com/aviation/coupers/
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