McGR
Senior Chief Petty Officer
- Joined
- Jun 19, 2004
- Messages
- 664
Many years ago (15+) I had bought various parts required for rebuilding my old 1956 30hp Johnson. This included a full gasket set, rings and a complete extra 30hp powerhead. I knew one of the pistons was scored on my motor, hence the purchase of the extra powerhead. So, years later I finally dive in and decide to finish what I started.
My first step was to get the pistons out of the core powerhead in preparation for the transplant. After pulling the pistons from the core I noticed that the wrist bearings from the core hade plain bearings, not rollers. Given this, it appears I really have a 25hp core.
So, the question is - Will they work? According to service information both have a 2 3/4" bore & 2 7/8" stroke. However, in the parts manuals they have different numbers 376794 for the 30hp and 375781 for a 25hp. Do any old outboard gurus out there know if these can interchange without major catastrophe?
My first step was to get the pistons out of the core powerhead in preparation for the transplant. After pulling the pistons from the core I noticed that the wrist bearings from the core hade plain bearings, not rollers. Given this, it appears I really have a 25hp core.
So, the question is - Will they work? According to service information both have a 2 3/4" bore & 2 7/8" stroke. However, in the parts manuals they have different numbers 376794 for the 30hp and 375781 for a 25hp. Do any old outboard gurus out there know if these can interchange without major catastrophe?