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Hello,
Looking to find out the thread size for the flywheel nut as well as the 3 screws that hold the rope sheave, thanks1 user thanked author for this post.
Guessing the nut is a 7/16″ x 20 tpi, and the three machine screws
the oddball 12-24 or 14-24, which are a little hard to find.
Do some searches on site for those oddball thread sizes to see
which one for sure. Guessing you already tried 1/4″ x 20?Prepare to be boarded!
Stanley is correct #10 – 30 tpi. AT first I questioned this, thinking perhaps the slightly more common #12 – 28, but no! I checked my A-25, sure enough #10 – 30.
I have posted this in the past, but its worth repeating in the interest of not messing-up a nice motor. Back in the day when the American National Screw Standard was commonly in use there were screw sizes from # 2 to #30. Some of these remain in common usage today, like #6, 8 , 10. Others like #3,7, 9, 14 are now obsolete. As for thread pitch, most of the old number sized had three “standard” pitches associated with a given size. For example the #10 (0.189″) came in 24, 30 and 32 TPI. The #12 (0.216″) which we encounter on our old motors came in 20 and 24TPI. Number 14 (0.242″)- 18-20 and 24TPI. Number 16 (0.268″) – 16, 18, 20 TPI. Where one can get into trouble when encountering these old screws is not only the unusual pitch… like forcing a common hardware #10- 32 into that #10 – 30 hole. Likewise the size, note how dangerously close the old #14 and #16 sizes are to the common 1/4′ (0.250) screws, Want trouble? try a common 1/4 – 20 into a #14 – 20 hole in your prize outboard. When in doubt, the micrometer and thread pitch cage are your friends.Joe B
Joe – What would this be?
Tubs
A "Boathouse Repair" is one that done without having tools or the skills to do it properly.
Tubs;
Its 1/4-20 NC but 0.010″ oversize. Probably a # 14 screw like Joe says. Whatever it is, I recently finished making a set of these bolts for an early Johnson, they hold the cylinders onto the crankcase housing. I didn’t use a die for the threads, I just cut them in the lathe.
Hope it helps.
Best,
PM T2He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...
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