Flywheel key for Neptune OB34A

[Buccaneer]

The rectangular flywheel key for my Neptune OB34A is almost
sheared. It’s 1-1/8" long, 1/8" wide, and a hair under
5/16" deep (about .270).
No such keys seem to exist, but I do find keystock
that’s 1/8" wide x 3/8" deep, that could be machined
down I suppose. Keystock seems to be offered
in carbon steel, zinc plated, stainless steel, etc.
What would be proper for a flywheel applications?
Carbon steel?
Thanks!

Prepare to be boarded!

[dan-in-tn]

I would probably lean towards the softer metals. Stainless would be nice as most is soft and rust/corrosion would be no problem. The key essentially locates the flywheel on the crank. Tightening it on the taper is what keeps it there. If you don’t feel good about the taper you can lap it in with valve grinding compound. That’s what we have had to do even on big V-6 engines!

Dan in TN

[kees]

I have made several of stainless steel and used some chemical compound on the taper.
your idea of using valve grinding is perfect , I will follow that advice! 😎

[Buccaneer]

Thanks for the reply. I was wondering why the key was half sheared,
but suppose that’s common with heavy flywheel engines. Good
idea to check the taper. I didn’t realize stainless was on the "soft"
scale. Thanks!

Prepare to be boarded!

[Author]

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