Evinrude 7516 7.5 hp Fleetwin Flywheel nut size?

[Mumbles]

Hey Buck, I just measured an AD crank with good threads for comparison and it miked out at 0.498 for the full length of the threads. ☺

[Buccaneer]

Mumbles, ".593" was a typo…… or lisdexia or something 🙁
I meant .493.
My micrometer might be "off" a tad, but I don’t think the
whole threaded area was expanded, but perhaps that’s
why the nut was missing,…. if someone beat it to death!
If you’re convinced OMC’s threading is a modern day
standard 1/2" x 20 tpi, then I’ll find a good die to chase it down.
A good share of my taps and dies were my grandfathers.
He died 40 years ago, and he probably got them used,
so it wouldn’t hurt to get a new die or two! …. P.S.-
they’re still better than the Taiwan flea market set
I got that you could’t even tap a stick of butter with!

Prepare to be boarded!

[amuller]

It has been my experience that grade 8 nuts from the hardware store or farm supply usually fit OMC crank threads unless they’ve been mushroomed by excessive pounding, in which careful use of a good die is the answer.

[fisherman6]

I have a 5hp Gale apart right now if you want me to go verify the size. I’m about certain it’s a 1/2-20 UNF thread but I’ll be happy to check it for you.
-Ben

OldJohnnyRude on YouTube

[Buccaneer]

Ben, if a regular "off the shelf" 1/2" -20 nut fits your Gale, that
would be good to know. Thanks!

Prepare to be boarded!

[fisherman6]

Buc, I don’t have an off the shelf 1/2-20 nut handy, but I went out and measured the thread. My Gale measures 0.497" major diameter the full length of the thread and my 20TPI thread pitch gage fits perfectly. I can assure you it is indeed 1/2-20 UNF thread. A standard grade 8 hardware store 1/2-20 nut should fit. If it does not, carefully chase the thread with a 1/2-20 die past the mushroomed end to restore the proper thread.
-Ben

OldJohnnyRude on YouTube

[Buccaneer]

Thanks Ben, sounds like I’ll have to purchase a die when I get to the
big town.

Prepare to be boarded!

[Author]

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