I have a 1959 Evinrude Fastwin 18 on a 14ft Starcraft semi-v John Boat. I have had this motor for about 10 years and have slowly repaired and replaced all the usual suspects and last summer I had the motor running great! However with my wife and 2 young children on board with me, the motor had trouble planing out the boat. I have turned it into a "bass boat" conversion with decks and seats so there is a little more weight compared to an unmodified aluminum boat.
I wanted to get more power out of my motor so I could plane out with passengers. I searched the forums and found lots of posts suggesting modifying your motor will make it run worse, but I wanted to try. A larger motor means more weight and I didn't want to go that route.
There's not much info out there about swapping parts or what carb or intake will fit what so I spent a lot of time researching. I found the best sources of info to be part sites, specifically looking up gaskets and matching part numbers from different years to my engine. Basically, if it has the same gasket it should fit.
I ended up with a cylinder head from a 1972 25 HP, intake from a 1984 25hp, and a carburetor from a 1984 50 HP. I had to make a custom linkage to get the carb in sync with the magneto plate, and drill out the high speed jet a few sizes in the carb but otherwise no issues. I used the original 1959 18hp reed plate because of design differences between the years, most having to do with the pressure tank and the little reeds for it.
Before the mod, I was able to hit about 16 MPH by myself and about 10-12 MPH with passengers. After the new parts I clocked 19 by myself and 15 with passengers and it planes out now. I used the gps on my fish finder to get the speed. Also it idles smooth, starts easy, and has no lag or flat spots. Overall good performance and more power.
Just thought I'd share....
I wanted to get more power out of my motor so I could plane out with passengers. I searched the forums and found lots of posts suggesting modifying your motor will make it run worse, but I wanted to try. A larger motor means more weight and I didn't want to go that route.
There's not much info out there about swapping parts or what carb or intake will fit what so I spent a lot of time researching. I found the best sources of info to be part sites, specifically looking up gaskets and matching part numbers from different years to my engine. Basically, if it has the same gasket it should fit.
I ended up with a cylinder head from a 1972 25 HP, intake from a 1984 25hp, and a carburetor from a 1984 50 HP. I had to make a custom linkage to get the carb in sync with the magneto plate, and drill out the high speed jet a few sizes in the carb but otherwise no issues. I used the original 1959 18hp reed plate because of design differences between the years, most having to do with the pressure tank and the little reeds for it.
Before the mod, I was able to hit about 16 MPH by myself and about 10-12 MPH with passengers. After the new parts I clocked 19 by myself and 15 with passengers and it planes out now. I used the gps on my fish finder to get the speed. Also it idles smooth, starts easy, and has no lag or flat spots. Overall good performance and more power.
Just thought I'd share....
