Help convert 91' johnson20 hp to 35 hp

[waterfowler15]

hey everybody im new here but will be a owner of a 91' 92' 20 hp johnson short shaft and would like to convert it to the 35,via reed plate,intake,carb ,my question is what part numbers to go after? the intake i want to get so i dont have to do any porting so the correct 35 part should avoid that? any ideas of how you guy have done it? this mod sounds doable thanks

 

[BigB9000]

Re: Help convert 91' johnson20 hp to 35 hp

Well, I know nothing about this. I looked up the crankcase, crankshaft, and pistons (all are the same) sounds good in theory.

0396790 MANIFOLD, Intake. 30 & 35 Models Only 1 $145.91 USD

Leaf plate is the same for the 35 and the 20, so you don't need that.

0432701 CARBURETOR ASSEMBLY. Not Shown 30 & 35 Models Only

Driveshafts are the same, gearcase internals are also.

 

[waterfowler15]

Re: Help convert 91' johnson20 hp to 35 hp

Well, I know nothing about this. I looked up the crankcase, crankshaft, and pistons (all are the same) sounds good in theory.

0396790 MANIFOLD, Intake. 30 & 35 Models Only 1 $145.91 USD

Leaf plate is the same for the 35 and the 20, so you don't need that.

0432701 CARBURETOR ASSEMBLY. Not Shown 30 & 35 Models Only

Driveshafts are the same, gearcase internals are also.

hey thanks for the reply good to know the leaf plate is the same, i will look in to the manifold, and carb and wait for more replys see how other have done on here from what i heard the carb and intake and your golden ,bit larger prop to slow down the rpm's? thanks again

 

[jasper60103]

Re: Help convert 91' johnson20 hp to 35 hp

I think johny25's thread will answer most of your questions....

http://forums.iboats.com/johnson-ev...rude-25hp-30-35hp-conversion-pics-532265.html

 

[boobie]

Re: Help convert 91' johnson20 hp to 35 hp

Is it worth the time and cost ?? I'd just buy a bigger motor.

 

[nwcove]

Re: Help convert 91' johnson20 hp to 35 hp

there is a mathematical formula that makes the conversion easy. X+Y=35 X being what you sell your motor for. Y being the extra cash you throw in to purchase a 35.

 

[waterfowler15]

Re: Help convert 91' johnson20 hp to 35 hp

hey,after reading your replys to if its worth it the motor is 600 doll hairs ,30hp carb rebuilt 130 doll hairs and 30hp intake is 10 so for 740 i would have a 91' 92' 30 hp that would push my duck boat and gear better than my 76' 25 which is fine with one guy but i want to rip on a budget of coarse

 

[waterfowler15]

Re: Help convert 91' johnson20 hp to 35 hp

update, i was able to find the intake for cheap 10 and am now looking for a 30 hp carb primer style from the early 90's ,any pics of the carb of should look for would be great thanks will post pics when i get her home