Thorp Air Command - T18.net

I have an O-290 powerplant that I am putting in my t-18. The log book that I have on this says that the crank was replaced with a O-320 crank. I needed a flywheel (assuming a o320) for this and found that someone on the forum had a O-320 flywheel for sale. I had it shipped to me and when I tried to fit it to the crank the holes on the flywheel are just a tad too big. the holes on this flywheel are 3/4", but my bushing flanges on the crank are about 5/8" O.D.

Are there different sized flywheels for the o-320 out there with different diameter holes for the bolts? I am a somewhat perplexed at what to do. Could there be some type of spacer that is supposed to fit there? I only have a o-290 parts and service catalog.... but nothing for the o320. Everything has been simple for matching parts until I got to this crank.

There are also 2 part numbers on this flywheel. The original etched numbers are #71328. Then right beside these numbers someone has penciled in 68867 (modified?).

If anyone has some insight, I would really appreciate it.

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Dean Cuke
Visalia, California
N772DM
KVIS

I'm in Boston and cannot check the part numbers, sounds like someone modified a 0320 flywheel to fit an 0360. The 0320 uses 7/16" bolts and the 0360 uses 1/2" bolts using larger lugs

I checked on that for Bill, and he is of course correct ...

71328 is an old PN for an 0-360 (superceded by 72565)

68867 is an 0-320 PN

That explains the oversized holes.

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Lee Walton
Houston, TX
N51863,N118LW
KEFD

That answers my question. Thanks Bill & Lee for your help. I really appreciate it.

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Dean Cuke
Visalia, California
N772DM
KVIS