1980 25 hp, can i use a 1986 head?

[dkonrai]

can i use the head from a 1986, 25hp on my 1980 25hp?
dino

[boats.net]

Not sure, they use different part numbers but not whats different.

[addict620]

80 vs 86

I think so. I've been building a lot of 1988/1992/1996 and 2005 30hp's lately.
Biggest concern would be crank and driveshaft length. That old 1980 driveshaft may have the 14splines required by the 1986 crank but may not seat fully? May double check the gasket from exhaust housing to powerhead as well. Can't prove it'll work, but I can't think of anything right off that wouldn't allow for it. To me if the crank, driveshaft and exhaust housing (where powerhead sits) all cross you may be good. The exhaust housings are going be completely different if your 1980 shift shaft couples mid-leg so if you need some pics of more modern 1986era mid section I can help. Hope this makes a bit of sense.

[dkonrai]

Originally posted by addict620 View Post

I think so. I've been building a lot of 1988/1992/1996 and 2005 30hp's lately.
Biggest concern would be crank and driveshaft length. That old 1980 driveshaft may have the 14splines required by the 1986 crank but may not seat fully? May double check the gasket from exhaust housing to powerhead as well. Can't prove it'll work, but I can't think of anything right off that wouldn't allow for it. To me if the crank, driveshaft and exhaust housing (where powerhead sits) all cross you may be good. The exhaust housings are going be completely different if your 1980 shift shaft couples mid-leg so if you need some pics of more modern 1986era mid section I can help. Hope this makes a bit of sense.

that all makes perfect sense. i got the head off ebay, it looks very clean and flat. head and water jacket look identical so it should work. most interesting that the head will fit so many years. so now its time to dress the head, clean off the old gaskets, clean the motor and slap it back together. seems so easy but right now i can only think of cold wet hands
have been reading up on these motors, and it seems that if i wanted to, i could get a larger carb and dremel the intake to match and have a 35? same cubic inches.
its a little cold to work on the motor (in the unheated garage). i guess its warm compared to the east but still cold none the less. its been in the 20's here out west at night, and mid 40's during the day.
dino