1928 Evinrude Model “U”……Morning everyone my question of the day is What is my spark plug thread…… It’s too large for 18 MM……. I have some pipe thread plugs it to is wrong and the pitch is wrong……
I want to fabricate a plug for the “grease gun method” to free the stuck cylinders. I don’t want to destroy my existing plugs as They may be useable. Thanks Jim
2Fast4Me
This topic was modified 4 years, 7 months ago by 2fast4me.
I believe that one is 7/8-18. Try to find a take-apart plug that size, find someone with a lathe, and replace the porcelain with an insert tapped for a grease fitting.
All the old “take apart” Champion plugs I have are 18mm. You are supposed to replace the copper washers on either side of the ceramic each time you took them apart to clean off the carbon. . impossible to find these washers today. – Some of the first Row Boat Motors were threaded to accept the ceramic insert held in place with a jam nut. These were developed as “Igniters” for the”coal oil” fueled steam engins of the day.
Thanks for the help Bob- looks like model A 1928-1931, Tom right on with the size, i verified it while at work. & Garry, I’ve got some of those “take apart” models also and thanks for the extra info.
I’ll prolly just order two new ones and get the process started.