Evinrude model U

[2fast4me]

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 5 years, 9 months ago by 2fast4me.

[Tom]

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.

T

[2fast4me]

Thanks Tom, i can handle the fabrication part if i can find the spark plug. I had no idea this size existed.Jim

2Fast4Me

[Bob Wight]

Same size as used on Model A Fords. You might try Summit Racing to find them.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[garry-in-michigan]

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.

• This reply was modified 5 years, 9 months ago by garry-in-michigan.

[2fast4me]

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.

2Fast4Me

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