1956 15hp Johnson carb differences with 1957 Elto 12hp

[Vintage Boat Guy]

I recently bought a beautiful 1957 12hp ELTO and it came with a beaten up 1956 Johnson 15hp. I've have a 1954 15hp Evinrude and I know that the 15s were replaced with the 18hp. My question is, what makes the Johnson and Evinrude a 15hp and the ELTO a 12. I've noticed a difference in the high speed needle, is this the only difference? Would changing the needle make the ELTO into a 15?

 

[Vintage Boat Guy]

Also would like to know if they take the same prop as the ELTO has a prop that is the same as my 18hp and it doesn't look like the proper one.

 

[racerone]

You might want to look into the ELTO-----As in does it have the same type of bearings as the Evinrude.-----Not sure if you would want to up the power on the 12 hp.

 

[Chinewalker]

The 12 may be a plain bearing motor. Not sure about the '57, though. Props will interchange, to a degree. Diameter and pitch are what you should be checking. Use what works best on the motor you're running.

 

[jimmbo]

I recently bought a beautiful 1957 12hp ELTO and it came with a beaten up 1956 Johnson 15hp. I've have a 1954 15hp Evinrude and I know that the 15s were replaced with the 18hp. My question is, what makes the Johnson and Evinrude a 15hp and the ELTO a 12. I've noticed a difference in the high speed needle, is this the only difference? Would changing the needle make the ELTO into a 15?

Richening the high speed mixture is not going to turn any engine into a higher HP model. More air and fuel together are needed for that.
Differences in porting, compression ratio, intake manifold/reeds and carburetor size are the most likely differences. As mentioned earlier, friction versus non-friction bearings may also be one the differences.

 

[F_R]

Everybody wants to make their motor something it ain't. To begin at the beginning, the 12hp is a 2-1/4" bore for 17.89 cubic inches displacement. A 15hp is 2-3/8 bore for 19.95 cubic inches. In addition the bearings are different as already suggested. But yes, they did come with the same prop. Reason? It is not desirable to rev up a plain bearing engine as high as what a roller bearing one can tolerate. So the seemingly too steep prop holds the RPMs down.

 

[Vintage Boat Guy]

So I guess the prop off the 15hp should be good for the 12hp. I'll leave the rest alone, didn't realize it had different bearings. I could imagine its the same as a gale of its year.

 

[F_R]

Yep, a Gale motor made in Canada. Also same as the Canadian Gale Viking.