Al, are you gonna get us any pictures of this??
This looks like a great opportunity of education on our part!

Yeah! I've still gotta get the Johnson power head off then I can compare the two side by side. I didn't think pics were needed in the disassembly process since it is in about every repair manual out there.

It may take me a few days. IT'S HOT DOWN HERE IN MISSISSIPPI!! Not to mention it starts raining every time you turn around.

Yeah, I've been putting off trying a different motor for the last 2 weeks because of the thunderstorms, bad tides, heat and work.
Seems all I want to do is drink bourbon and ice when the weather and work don't cooperate with the boat schedule!
WE STILL WANT PICTURES!!

OK! OK! OK!

Here are some of the problems with the Johnson

http://img139.imageshack.us/img139/7...0209161102.jpg
Rusted steering arm bolt

http://img141.imageshack.us/img141/5...0209161101.jpg
Busted cavitation plate.

http://img139.imageshack.us/img139/2...0209161100.jpg
Lower pivet bushing absolutely GONE!

I've got a leaking tilt/trim motor, tight/sticky throttle and other nit-picky problems. When I get the motors ready for the swap I take more pics.

Dat's what i'm talkin about!!
Pictures!!

I forgot one -

http://img231.imageshack.us/img231/8...0209161000.jpg
These bolts are so rusted that I can get them to budge. What is the best way to get them out? Cut the head off and take the shank out when the power head is off or what? Any suggestions?

That's a long way thru corrosion to get to the threads.
A combination of heat, impact driver, even trying to soak the threads will make you cuss.
Chances are, they are gonna wring off about 1/4" from the head. At least you can tap the housing and remove it to spray and heat the bolts.
An impact driver has been effective about 25% of the time also.
http://www.harborfreight.com/cpi/cta...emnumber=93481

It's actually just the head. There was another one that was about that bad. I was able to get it out and just the head looked that bad. There was powder corrosion on the shank down but not rusted.

that white power is what steel and aluminum make when in saltwater, you can completely kill the midsection but cutting the sides of the bolts jackets with a grinder and cut off wheel to get them out.

I know you need to be careful swapping powerheads on some of these engines as tuners and adapters were changed from year to year as well as tuners. The 88 150 is actually the equivelant of an 82 175 in most respects to port timing and such. Go ask the MERCURY guys about following the idea that just because it will bolt on it will work, many a MERC has been fried that way. I'm not saying it isn't possible, but you have to check alot of variables when doing it. Also in 88 most of the cross-flow V-6's had gone to large bore engines whereas in 82 they were all small bore for the most part. Many times they would make a slight change in the cooling jackets or something and it would cause overheating if you didn't have the matching deflectors in the mid. Also the carbs changed in 83-84, as well as the heads were opened around that time for unleaded gasoline with lower octane ratings(this is why OMC offered the low compression heads as an accesory if you didn't want to run 89 octane). Also you have to pay close attention to the exhaust portion as it goes through the midsection adapter, I know they changed them some time in the early 80's to a different design and you had to do some JB welding to avoid overheating if you swapped to a newer mode powerheadl or vise versa.