58 Lark, different flywheels, same part number?

[DavesInvader]

Hi folks,

The 35hp, 58 Lark 35515 I'm working on has a flywheel on it with the cogs for a generator belt, but my motor has no generator, so I suspect it may be a replacement flywheel. The part number stamped into it is 580232. It does not have the inspection hole in the top that you can use to set the points. So in order to set the points on this motor I have to remove the flywheel. I've been thinking about finding a flywheel with the inspection hole to make setting points easier down the road.

A local guy has a flywheel he says is also from a 58 Lark but his is a 35514. The number on his flywheel is also 580232. His flywheel does have the inspection hole. What's up with this? Would they really have two different flywheel designs (one with generator belt cogs and no points hole and one without generator cogs and with points hole) under the same part number (or did I just write down the wrong number from his?)

To make matters weirder, my parts manual diagram gives 580285 as the flywheel number for my motor.

I'll probably be picking up the flywheel from the guy this weekend and trying it out on mine to make sure it fits, but the whole thing just strikes me as odd.

 

[CATransplant]

Re: 58 Lark, different flywheels, same part number?

Sometime back in those days, OMC changed the design of the flywheel for the 35hp models. Apparently, the ones with the holes could develop cracks, and cracks are not a good thing at all in a flywheel that is spinning around at 5000 RPM.

I suppose they kept the same part number because there was no reason not to, and the new part was the correct replacement for the old one.

I had a 58 Johnson 35, complete with the flywheel with the inspection and point-setting port. No cracks in mine.

 

[Joe Reeves]

Re: 58 Lark, different flywheels, same part number?

The number of 580232 is simply a factory casting number. Look closely at the generator pulley..... you'll no doubt see three (3) areas where locking screws of some kind are installed which keep the accessory pulley in place... a ad on pulley. Your flywheel is the correct one.

Your friends flywheel, cast number 580232 will fit also. The confusion is simply that a modification was made to the original flywheel factory mold to eliminate the point setting hole.

 

[F_R]

Re: 58 Lark, different flywheels, same part number?

Both of the above replies are correct. The early flywheels had a cracking problem around the hub. It was modified with a different hub, and the inspection hole was eliminated. There is a service bulletin to that effect.

The zinc pulley usually stretched and fell off. You will find very few of them still intact. That too was changed in later years.

 

[DavesInvader]

Re: 58 Lark, different flywheels, same part number?

Thanks guys, it all makes sense now!