Mercury 85 to 50hp powerhead swap

[bigpond]

I have a 1977 Mercury 50 hp motor that has a bad powerhead and found a great deal on a 1976 85 hp powerhead but I really don't know if I can swap it with my current 50 hp powerhead. It doesn't have any of the electronics or anything but all of mine are in great shape. My motor serial # 4808418....the 85 hp serial # 4540543. Any help is appreciated.

 

[racerone]

Re: Mercury 85 to 50hp powerhead swap

?????-----I really think this will not work. ----For one thing the crankshaft splines are different, plus a few other things.

 

[Chinewalker]

Re: Mercury 85 to 50hp powerhead swap

In a word... no. VERY different powerheads.

 

[bigpond]

Re: Mercury 85 to 50hp powerhead swap

I figured that, but I thought I would ask to make sure. Thanks for the replies.

 

[Doc279]

Re: Mercury 85 to 50hp powerhead swap

I have a 50hp powerhead that I am not going to use. I'll see if I can get a compression test done and give you those numbers. My 50hp has bad wiring and a bad lower gear housing - I bought it for spare parts - have never heard it run. It does turn over and appears to have good compression.

Let me know if you might be interested. Happy New year

 

[bigpond]

Re: Mercury 85 to 50hp powerhead swap

Doc, that is a good option. I plan to tear into mine here in the next couple of weeks. Obviously if the price is right I would definitely be interested. I think mine broke a connecting rod, but not sure how much other damage there may be. Let me know what you are thinking you want for your powerhead.

 

[Doc279]

Re: Mercury 85 to 50hp powerhead swap

Will do - I can get compression readings in the next few days for you. I am laid off for the month.
Let me see what I can do. I know that is is a 1973 or 74?

 

[bigpond]

Re: Mercury 85 to 50hp powerhead swap

Doc I just wanted to let you know I found another engine. I tore mine apart and it had a pretty big gouge in the #4 cylinder. I found another complete engine minus the lower end for $100 and couldn't pass that up with all the spare parts. Thanks for the offer though.

 

[Doc279]

Re: Mercury 85 to 50hp powerhead swap

It's cool - that is a decent price. With the little bit of snow and the bone chilling cold that we have had I had not been in the garage.
Let me know if you need anything - I have several of these old engines and a really good Mercury service manual for the years.

Good luck with you project!!