3 cylinder evinrude/ johnson???

in the years the 3 cylinder was built it had 50 to 75 hp. out of all thoughs years is any one block better to use for racing? thanks steve :)

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Originally Posted by David_L6

I don't think anyone uses the very early motors. Go for something from the mid 1970's on up. I can't see where any year model would be any better than any of the others given that there are hardly any rules for the class. I don't think anyone is running a motor in stock form.

Someone needs to try to get Steve Benson on here to answer questions about those hernia waiting to happen motors.

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there are a few guys that do run the OMC 3holer "as stock" bolted onto a racing tower that I know of and they are still fast........shake, rattle and roll!!! More of the "shake" though.......

Steve B. is the 3holer man though!!!!!!

In the first couple of years of that motor, when they were advertised as making 55hp, they used dome-topped pistons and had only two transfer ports. OMC boosted the power to 60hp with the addition of a third transfer port (in the form of a big boost-port), and used flat-top pistons and much stronger rods. Someone else will have to tell you what changes were made after that, but the 60hp version can be built to make a pretty good racemotor. These triples shake pretty hard, however. Jim Hallum built one, driven by Gerry Walin and Bob Rhoades, and gave it to me to repair after it cracked the block next to the top cylinder liner, next to one of the ports. You'll see a sharp corner there which is a stress-concentrator; possibly you can figure out a way to radius it or peen it so it will be a little less likely to crack. I don't know where Hallum's motor is now; I did the welding on the pulse-tuned exhaust system after Jim designed it and formed the sheetmetal, and I wonder how it has held up after all these years. Jim took some big 2bbl carbs and reedblocks (from V-4s) and adapted them for alcohol. If the APBA has a section in the hall of fame for tuners, Hallum should be a charter member!

after that the cases changed mostly on the exhaust side, to the two brige three hole seperate exit ports, in the 74 service manual you can see shots of the old style case, 75hp cases are best factory ones. the vibration is from the heavy
pistons at high revs.
a fresh stock 75hp with some 3 jet carbs, a tight head and a good pipe
and your in it :cool:

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Originally Posted by smittythewelder

In the first couple of years of that motor, when they were advertised as making 55hp, they used dome-topped pistons and had only two transfer ports. OMC boosted the power to 60hp with the addition of a third transfer port (in the form of a big boost-port), and used flat-top pistons and much stronger rods. Someone else will have to tell you what changes were made after that, but the 60hp version can be built to make a pretty good racemotor. These triples shake pretty hard, however. Jim Hallum built one, driven by Gerry Walin and Bob Rhoades, and gave it to me to repair after it cracked the block next to the top cylinder liner, next to one of the ports. You'll see a sharp corner there which is a stress-concentrator; possibly you can figure out a way to radius it or peen it so it will be a little less likely to crack. I don't know where Hallum's motor is now; I did the welding on the pulse-tuned exhaust system after Jim designed it and formed the sheetmetal, and I wonder how it has held up after all these years. Jim took some big 2bbl carbs and reedblocks (from V-4s) and adapted them for alcohol. If the APBA has a section in the hall of fame for tuners, Hallum should be a charter member!

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This motor is still in the N.W. hanging in a guarge. I agree that Mr. Hallum is very wise and a great tuner of engines. He is just no longer enthused about building race engines, but still works on them at the local marina in Everett Wa.

3x2's:eek: :cool:
http://img471.imageshack.us/img471/9...uff19ce.th.jpg:cool: :eek: