new 175 setup problems

[hazard]

Hey all, I have an 82 Checkmate Exciter and it had an Evinrude 115 on it. Boat is ~20' long. Ran great with the Evinrude, but I upgraded this past weekend to an 86' Johnson 175hp motor.
The transom height on my Exciter is 23" and the shaft on the new motor is 25". Here's my issue, I put the new motor on and i lined up the fin (i think its called the caviation plate or whatever that fin is above the prop) with the botom of the boat. The motor is mounted in the top holes.
Well, i took it out for a trial run today and man does it have alot more power! BUT, I had alot of water coming in from in-between the transom and the motor up into the transom "well" area. There was also a large spray of water on either side of the motor at any speed almost as if something were dragging in the water.
Not to mention that when I trimmed the motor, the boat got immediately unstable. Any thoughts? Does it need a jack plate? Is 25" too long?
Help!

[hazard]

Some pics. The motor is a little dirty from being put on
http://i20.photobucket.com/albums/b2...0/newmotor.jpg
http://i20.photobucket.com/albums/b2...175johnson.jpg

[Towndrunk]

That boat was made for a 20" motor and you have a 25 " on it? Not a good move. You need to get it changed over to a 20" or try a plate that will get the nose of your motor app 1" below the bottom of the boat. I don't reccomend a plate as it will put your powerhead too far up but it's up to you.
TD

[hazard]

That boat was made for a 20" motor and you have a 25 " on it? Not a good move. You need to get it changed over to a 20" or try a plate that will get the nose of your motor app 1" below the bottom of the boat. I don't reccomend a plate as it will put your powerhead too far up but it's up to you.
TD
Well, it had a 20" on it, but the transom is 23" long. Its a weird in-between size. I bought the motor off of an Evinrude tech and he put it on for me. When you say "nose of the motor" what do you mean? The front of the prop?
The caviatation plate is flush with the bottom right now. It sounds like it needs to be lifted up.

[Towndrunk]

Well, it had a 20" on it, but the transom is 23" long. Its a weird in-between size. I bought the motor off of an Evinrude tech and he put it on for me. When you say "nose of the motor" what do you mean? The front of the prop?
The caviatation plate is flush with the bottom right now. It sounds like it needs to be lifted up.
If the tech sold you the motor he knew better. Take it back to him and tell him he screwed you over by not telling you it was too long for your boat. Get your money back or insist that he make a 20" out of it.
Nose of lower unit is what I meant. The part that is closest to your boat.
Opposite end of your prop shaft.
Yes, it needs to be raised.

[hazard]

If the tech sold you the motor he knew better. Take it back to him and tell him he screwed you over by not telling you it was too long for your boat. Get your money back or insist that he make a 20" out of it.
Nose of lower unit is what I meant. The part that is closest to your boat.
Opposite end of your prop shaft.
Yes, it needs to be raised.
I'm going to raise it up two holes and see what that does. Like I said, it is in the top hole now, so it can go up. Thanks for the advice!

[Xlration Marine]

Put your motor up 5" from where the other one "sat". Land and sea makes a kit for that. It's an ok move, 25" shafts are more abundant and cheaper to buy than the 20". You might want to look for a used manual or money permitting a hygraulic jack plate. Get that puupy set and she will haul the mail. Good Luck.