F90 shaft swap

[spankeyis]

I have 2 4 stroke F90’s . The 25” shaft has a cracked block. The 20” shaft has a good motor so I want to swap them. Can I bolt the 25” shaft to the 20” motor if I change the housings and such? Is it a direct bolt on?

 

[spankeyis]

Question 2. Would it be easier to just swap power head instead? Engine is on a stand and needs t the vessel.

 

[racerone]

It is a lot of work to make the switch.----Easiest one is the 25" to the 20" if you have the 5" spacer for exhaust housing.

 

[KJM]

I don't know anything about the switch but I was wondering how the block cracked? I'm curious because thats the same motor I have.

 

[spankeyis]

It is a lot of work to make the switch.----Easiest one is the 25" to the 20" if you have the 5" spacer for exhaust housing.

Clarification…So put the 25” lower/mid on the 20” P90 motor?

 

[racerone]

Clarification.----Is there a 5" spacer used on the 25" motor ?

 

[spankeyis]

Clarification.----Is there a 5" spacer used on the 25" motor ?

No.

 

[racerone]

You can't bolt a 25" lower unit onto a 20" midsection.-----This requires major work whichever way you look at it.----If you need a 20" motor for your boat than have a shop change out driveshaft and shift rod from 20" lower to the 25" lower.-----Time to look at the parts and think this over..

 

[stresspoint]

as posted the best option is to remove the powerheads and swap them , less effort and will only cost you a gasket.
iv done it with a F100 , easy job .remember to put some sealer on the bolt threads otherwise next time you need to remove the power head it makes it hard if a bolt seizes

 

[spankeyis]

No.

Correction! Yes I have the 5 inch spacer. I forgot I had slid it off and set it aside. So I have a complete 25” shaft on a cracked power head. Can I take the power head off a P90 with a 20” shaft and just bolt the power head on the motor that is blown. Sorry for the confusion. I guess the real question is will the shaft splines mate up?

 

[stresspoint]

Correction! Yes I have the 5 inch spacer. I forgot I had slid it off and set it aside. So I have a complete 25” shaft on a cracked power head. Can I take the power head off a P90 with a 20” shaft and just bolt the power head on the motor that is blown. Sorry for the confusion. I guess the real question is will the shaft splines mate up?

that's what i said in the post above to do , easy peasy.

 

[boscoe99]

Correction! Yes I have the 5 inch spacer. I forgot I had slid it off and set it aside. So I have a complete 25” shaft on a cracked power head. Can I take the power head off a P90 with a 20” shaft and just bolt the power head on the motor that is blown. Sorry for the confusion. I guess the real question is will the shaft splines mate up?

P90?

 

[boscoe99]

Changing the power plants is the easiest and fastest way to go.