25HP driveshaft 4 spline ?

[GYPSY400]

Hello all, Newbie here...

I'm having a problem finding parts for a 19?? evinrude engine.. What i am trying to do is install a 25hp evinrude powerhead onto a 1982 johnson 25hp chassis.
I have discovered that the exhaust housings are different so I will need a 1982 evinrude exhaust housing (as per the BRP online parts diagram the evinrude housing and gasket are different than the johnson)

But my biggest dilemma is the driveshaft.. The johnson gearcase has a 14 spline driveshaft and the evinrude engine has a crankshaft for a 4 spline driveshaft.. So can anyone tell me what year evinrude engine used a 4 spline driveshaft?? if I at least know the year I can further reasearch the proper parts. Thanks

 

[jbjennings]

Re: 25HP driveshaft 4 spline ?

I'm not sure what's up here. The johnson and evinrude should use the same driveshaft. the bottom of the driveshaft is 14 spline and the top where it connects to the crank should be a 4 spline on all of them. I can't imagine there being a difference. You may need to recheck to see what your parts diagram is showing, perhaps there is an error there. It would be helpful if you knew what year evinrude you have. How are you making parts comparisons if you don't know what year your evinrude p-head is? Seems like that would be where your problem may be.
JBJ

 

[14ftgrumman]

Re: 25HP driveshaft 4 spline ?

The 4 splined drive shaft is from an older engine, If you have a lower end that has exhaust thru the hub, the power head that you have is not going to fit. The power head you have is used up to the mid-late 70's. The crank is actually a 3/8" square drive. (The old style) the splined drive shaft is the new style. Check the parts brakedowns for a 25 HP of the early to mid 70's. This is the power head that you have.

Some one correct me if I'm wrong, please.

 

[GYPSY400]

Re: 25HP driveshaft 4 spline ?

Ok thanks guys! When I had bought the powerhead, the guy told me it was from the "same vintage" And it does look the same aside from the exhaust tube and crankshaft spline. the exhaust on my 1982 chassis is not thru-hub. I had another person email me and say the powerhead was pre-1976. Now I have to find a cheap driveshaft and exhaust tube.

 

[14ftgrumman]

Re: 25HP driveshaft 4 spline ?

Not sure that a drive shaft and exhaust tube will make it work. Is the bolt mounting pattern on the power head the same as the chassis,mid section,the part that the power head bolts to? Will the different exhaust chamber fit in the chassis?


Don't shoot the messengers.

 

[GYPSY400]

Re: 25HP driveshaft 4 spline ?

Not sure that a drive shaft and exhaust tube will make it work. Is the bolt mounting pattern on the power head the same as the chassis,mid section,the part that the power head bolts to? Will the different exhaust chamber fit in the chassis?


Don't shoot the messengers.

yes the bolt pattern is the same on the bolts that attach the engine to the chassis.. the only difference is one bolt in the middle doesn't line up for the exhaust tube.

Now is my information correct being the 4 spline shaft is pre-1976??

 

[14ftgrumman]

Re: 25HP driveshaft 4 spline ?

Go to shop.evinrude.com, compare part numbers for pre and post 76 25HP engines.
I've got 2 1972's-1 25HP and 1 20HP. They both have the 3/8 square drive. I also have 2 spare powerheads and they too have the square drive.