OMC Flywheel puller screw spacing

[fisherman6]

Hi All,
Does anyone know off-hand the bolt circle diameter of the three 1/4-20 tapped holes for the flywheel puller in the Classic OMC flywheels up to the FD?
-Ben

OldJohnnyRude on YouTube

[vintin]

Ben it looks like it is 1 and 7/8" on an RD. Don’t know if it is the same size as what the motors you are searching for.

or 1.875".

That was eyeballing it with a tape measure.

I got 15/16" center of the crank to center of one of the bolt holes.

[frankr]

After driving myself crazy, trying to confirm Vin’s measurement, I conclude he is correct—-for an RD. BUT, not all are created equal. I was measuring a 7.5 Fleetwin and it is a smaller circle. I reckon that is why OMC made their pullers slots instead of round holes.

[fisherman6]

Hi Dan,

Thanks for the RD dimension. I will use that one too. The FD’s and lower HP’s do have a somewhat smaller BC. Maybe someone will come up with that one too. I’m working one something and I have room for both patterns in the same part.

-Ben

OldJohnnyRude on YouTube

[fisherman6]

Hi Frank,

Thank you for the confirmation of Dan’s dimension for the RD. I found out they were different when I needed to get the flywheel off my RDE-16. I had made a puller for the smaller motors already and it didn’t fit the RD flywheel. I used hole transfers to mark the locations for the puller holes, so I had never measured either of them even though I have made pullers for both. I’m trying to draw up part of another device I’m working on while I’m at work and away from my motors. I will put both hole patterns in so I can use it for either size flywheel. I’m in complete agreement that the reason OMC uses slots in their puller is due to the different BC sizes for different size engines. I would rather not slot my holes for this application even though I’m sure it would work fine. It is more setup time for me and I have room for both patterns.
-Ben

OldJohnnyRude on YouTube

[frankr]

OK, I threaded bolts into two of the Fleetwin’s holes and measured the distance between them with a caliper, and using that info made a CAD drawing.
Long story short, I came up with a bolt circle of 1.628". Attribute the error to measuring and exact bolt diameters, I conclude it is a 1.625" bolt circle (1-5/8"). Whew!

[fisherman6]

Thank you Frank! I sincerely appreciate your efforts. 🙂
-Ben

OldJohnnyRude on YouTube

[kerry]

Wow, I must really be Old School… I used to have various cans, soup to coffee, with the ends cut off, and sliced down the side. Slid one end in as a slip fit, like a ring compressor, until it matches close to the holes and taped until measured with a tape measure. Always got close enough for "garage engineering". 😀

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