81 merc. 225 black max question

[bridgeman]

The speed novelty is wearing off quick with every trip to the pumps. My boat is currently rigged with twins now (25" shaft)and want to go with a single. I know that I need a 30" for single application. If I can extend the foot another 5" I'll save the other outboard for parts when needed. Do they make an extension kit for an 81?

[Bigshrimpin]

The answer is a little complicated. You can, but you won't be able to use your mid section. The 225 uses a 5" spacer already on 20" midsection. Maybe you can find 10" studs and a 5" second spacer, but those studs will have to be custom made.


The way I would do this . . . is by using a newer 25" midsection (I have a bunch of these) and using the a 5" spacer and studs on the existing 25" V225, a
a 28 5/8" copper tube (water tube), and a 5" Drive and 5" shift shaft extension from Bay Engineering.

http://www.baymfg.com/mercury.asp

One thing I am not sure of is how well these extension shafts work with your older preload Pin style lower units (1983 and earlier) . . . good question to ask BayMFG


If you want I'll be doing this conversion for mid 80's 200hp in the two weeks (from 25" to 30"). I can post a how too tutorial.

The hardest part is going to be removing the powerhead from the mid section on your motor. 28 years of salt and dissimilar metals will have made enough aluminum oxide powder to put a permanent choke hold on those powerhead bolts. PM me . . . I know a few tricks if you decide to do this.

[Bigshrimpin]

Here is a picture of a newer 25" Mercury. 1990/91 and later had this longer 25" midsection. If you can find a donor motor (check local merc dealers) . . . you can bolt up your powerhead to the mid-section . . . it'll give it a newer look too Just make sure that the T+T works and that the sterring arm and bottom yoke isn't rusted to hell. You can put your spacer on this mid and go 30" with a 5" extension.

[bridgeman]

Bigshrimpin .. Most likely more of a PIA than I anticipated, thanks for the info. Just going to have to learn to resist pushing the throttles all the way forward for a few years until I can upgrade to something newer in the way of power.

[Bigshrimpin]

Those old 1981 v225 are tough engines . . . they can take a LOT of abuse. I wouldn't hold back running them WOT . . . just make sure the idle stabilizer/spark advance modules are gone. The stock wh-20 carbs on that motor will drink some fuel, but the sound from those engines is awesome . . . kind of like a nest of angry hornets when turned above 6,ooorpm.

I ran one for a few years with wh-22's carbs . . . burn was only 10/11 gph @ 4000rpm and 20/21 gph WOT.

[bridgeman]

wh-22 carbs? where can I get them? motors run great but they're a bit thirsty.