Model U Speeditwin Specs Help

[gearhead4]

Looking for a little help with my Model U Speeditwin project. I took it apart to replace the left piston due to a cracked skirt from being hit and it was distorted. Honed the cylinders till cleaned and found that the clearances are very out of whack for the right piston and cylinder and the new piston I have for the left is just too tight. I need all the specs and a manual for this engine if possible (copies are A okay!) so I can ensure I have the right setup.

I have 2 very nice original 3 ring pistons with the third ring on the skirt but the clearance is would be too much if you ask me. I’ll have to go remeasure everything as I didn’t write it down last night.

Hoping to have this engine done soon and running!

All help is greatly appreciated and I’ll try and get some photos later.

[george-emmanuel]

Evinrude manuals back then are only parts,–no specifications. There are specifications in the Evinrude Service Manual reproduced by American Outboard Motor (Dora Kowalek).
Here’s what I have: Piston clearance 1928-31, .009–.0101: Piston ring part # 100055, # of rings–3, Diameter of ring 2.750, Width .1240-.1245, Compression lbs when compressed 6 1/2, Gap clearance .030-.040

I can supply a copy of the parts manual if needed….let me know.

George

[gearhead4]

Thanks for the info. Seems the little bit I have was good, wanted to be sure. A copy would be great George! I’ve been on the hunt for old manuals just keeping my eyes peeled for anything I could use.

My email is b16hydro@yahoo.com

Thanks,
Matt

[garry-in-michigan]

An early use of anti friction bearings. It did well and was quickly copied by Elto and Johnson. The racing model had dual carburetors.

[garry-in-michigan]

The 6304 E. Jefferson Ave address in the above ad was Michigan Marine owned by George K, Cheatham. George started as an Elto dealer in 1923 which added Evinrude in 1929. I went to school with his kids, George King and Dickie. He became a Johnson dealer in 1947 in a dispute over not being able to get as many Evinrudes as he could sell. Demand was higher than the factory could produce, and dad allocated motors according to what was sold in 1941. Evinrude was running more shifts as they hired and trained people to build the motors. It was a real headache for quality control. Elto production was eliminated in order to produce more Evinrudes. Galesburg was furnishing motors for several companies. Gas was cheap and jobs were plentiful. What we now call "The good old days" … George had a heart attack and died in the mid ’50s. The last I saw of his son George King, he was running service for Sears. The younger boy, Richard, was injured in Marine Corp basic training, got a disability pension, and became a minister … the fortunes of War . . . 😉

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