Chevy flywheels

[Jordan Baker]

Hi all

Today I cleaned up the flywheels I have for my engine. The left flywheel (#839754) is the original one that came with the wartime army 216 engine. The right side one (#3705410)is the one that came with the late model 216 I bought to put in my truck. After counting the teeth I found the right side one has 168 teeth making it a 12v flywheel. I’ve been told and read that flywheels and ring gears can easily be swapped around on the Chevy inline six engines.

However when I put the left flywheel one onto my engine,there is a small gap between the flywheel and the crank flange. See the second picture with the red arrows. Furthermore the 6 mounting bolt holes are for smaller diameter bolts then what the crank flange is drilled/threaded for. The dowl pins all line up just fine. If I was to use the early flywheel I would have to drill out the six mounting holes to accommodate larger diameter bolts on the crank. I can’t see that causing any issues. Would the gap between the crank flang and flywheel matter at all?

If I use the flywheel that came with the engine, I’m faced with the ring gear having 168 teeth versus the 139 teeth I need for the 6v starter. These rings gears are not compatible due to a slightly different overall diameter of the actual flywheel. My options would be to remove the 168 teeth gear and have the flywheel turned down to fit the 139 teeth ring gear. The positive of this would be that the flywheel would fit tight against the crank flange and the 6 mounting holes would be correct. I could also use the 11” clutch.

[David Herbert]

Would the pinion from a 12 v starter fit a 6v starter ? It might give you more options.

David

[Grant Bowker]

Based on the information in this thread, https://www.stovebolt.com/ubbthreads...&Number=602652 I think the answer is "no".

[Phil Waterman]

Hi Jordan

Swapping the ring gear no big deal, carefully drive off the gear using an oak block working your way around the flywheel. I've heard of people just heating with a torch but I'd be afraid of taking the temper out of the gear. As to heating the gear to put it back on http://www.mapleleafup.net/forums/sh...ear#post185072 I like an oven first time I did it just kept raising the temp of the oven a little at a time till found the temp where it just dropped on.

Of course be sure to have the tooth bevel to the front, yup first time I did it had it backwards.

As tho matching tooth count by flywheel numbers, I've got a collection of flywheels and have found both tooth counts with the same numbers, think this because of mix and match games that many of these engines have seen over the years.

Last two times I played this game it was to put six volt ring gears on 12 volt 235 and 261s. I was concerned about balance with changing flywheel and clutch assemblies, but the engines seem very smooth so didn't get fancy and seen the units out to have them balance as a unit.

Cheers Phil

[Jordan Baker]

Any thoughts on putting the 6v flywheel on my crank? It will have the gap between the crank flange and the flywheel hole. I’d also have to enlarge the 6 mounting holes?

[rob love]

I was faced with this back in the mid 90s when I did a truck for the Saskatchewan military museum. I removed the ring gear from the flywheels, turned down the 12 volt flywheel, and installed the smaller gear onto that flywheel. Worked, but since the lathe I was using was a brake lathe, I am not sure I got the balance completely right. I would suggest getting a real lathe to do the turning on, and then get the flywheel balanced afterwards.

[Robin Craig]

Jordan,

Having worked in an automotive and heavy duty machine shop I have done ring gears many times.

It isn't rocket science, more like good old fashioned bull work with some accuracy and some speed

Having one piece of ply thick enough to exceed the thickness of the ring gear works best.

Heat the ring gear using a neutral flame on an oxyacetylene torch with a cutting tip and heat it all the way around in a circular motion.

Grab it quickly with gloves and set it on top of the ply and using oak or aluminum or brass drifts hit the ring gear a good solid whack in once place and move around the ring gear swiftly, if you have heated it good and you move fast it will move a fraction as you go. Hopefully you hit your drift with a good size hammer and with purpose.

To install on the other one you will need to heat it up all around again and fast and using proprietary tools grip it and drop it on and again if required drift it back into place as it cools.

I guess I am being glib as we did them a few times a week.

There are plenty of youtube university videos to aid you.

Have fun

[Paul Singleton]

Hi Jordan, I think that you could have a bushing made to take up the space on the crankshaft. Use lock tight bearing mount to hold it in place, and drill out your flywheel out to fit the larger bolts. I don’t see you having any problems doing it this way.
Paul