Powerhead interchange

[ACAMS]

Will the powerhead off a 1984 Evinrude 60 HP 2 cylinder fit on a 1991 Johnson 40 HP 2 cylinder?

I checked and the cranks are the same part number, but somebody told me the bolt holes are different ... (he was full of crap on other things he told me, and I think he is full of it here too!)


Does anybody know what is different on a 60 and a 40 they have the same crank and pistons!

 

[MWG2600]

Re: Powerhead interchange

check the parts listings on brp's website. they show exploded views for all motor!

 

[Chinewalker]

Re: Powerhead interchange

The key part to look at would be the powerhead base gasket. If it's the same gasket, it should bolt up...

 

[ACAMS]

Re: Powerhead interchange

Thanks, the gaskets are the same, so I am going to assume it will work and go ahead and buy the 91 Johnson short shaft so I can have a 60 HP short shaft.

I am still wondering what makes the 20 HP difference since they have the same crank and piston?

The carbs are different numbers, but I can't see 20 HP from just a carb!

 

[Chriswalden]

Re: Powerhead interchange

Well it would appear, if I'm looking at the correct models #'s, the heads are different. That small change in the heads can create more cubic volume inside the combustion chamber, and more volume = more power. Then throw the bigger throated carbs in there to allow the bigger combustion space to breathe properly, you have more HP.

 

[ACAMS]

Re: Powerhead interchange

Actually, LESS volume equal more compression and more HP, OH-WELL, I guess it doesn't really matter unless it has a less restricted exhaust housing, then I am going to lose some of my 60 HP, but since it is going on a 16ft flat bottom jon boat I guess it won't hurt much.

 

[Chriswalden]

Re: Powerhead interchange

The fact could be argued. You can increase HP one of both ways more volume for more HP or less volume more compression more HP.

 

[1946Zephyr]

Re: Powerhead interchange

The best thing to do, is match up powerhead base gaskets to see. Someone who knows, will chime ine, but this is the approach that I would take. I'm sure that even they will mount up, with each other, you will have some other modifications to make.