Question...

[Destroyer]

Originally Posted by spareparts

Ok, lots of confusion here
Fist of all, it sounds like its a Johnrude Oceanrunner series with opical igniton. Pretty good motor, lighter than most. Its whats referred to as an Eagle Series. Its not as big or heavy as the 200/225 loopers. Bad part is parts are starting to dry up for them as Bombardier is starting to reduce inventory of older motor parts. Yamaha made s Saltwater Series and used carbs or the OX type fuel injection. I don't think this motor matches the details you've given. If the motor mentioned is a nice clean fresh water motor, then its worth that much at a premium.
As far as you going back merc, I've got a 5" extension and several 25" lower units laying around. Once I get this one boat in my yard finished, I may be able to free up some parts if you need.

Actually, since I have time, I was sorta thinking about bringing it down to you and letting you do it. (ROAD TRIP!!!) Do I really need a 25" lower unit? Can't I just use the same lower end with the extension and a different drive shaft? What about the shift rod and the pick up tube?

Yes, The engine is a Johnson. Sorry for any confusion. It looks very much like my Merc though.. not the wide spread cowl of the 90* engines .. more like the narrow cowl of the 60* Mercs. ( I know the degrees are probably off, but you get the idea.. it's a narrow engine. Very nice looking. It's not a freshwater engine though.)

[THEFERMANATOR]

The engine you describe sounds like a 60 degree looper OMC which is like Spare said an optical ignition system engine. VERY good engines, and easily argueably the best engine OMC EVER turned out. They are also one TOUGH SOB. As for the extension on your MERC driveshaft, this is pretty unadviseable even from BAY who makes the adapter kits. It is ALWAYS best to go with a 25" lower unit with the spacer kit.

[Destroyer]

Originally Posted by THEFERMANATOR

The engine you describe sounds like a 60 degree looper OMC which is like Spare said an optical ignition system engine. VERY good engines, and easily argueably the best engine OMC EVER turned out. They are also one TOUGH SOB. As for the extension on your MERC driveshaft, this is pretty unadviseable even from BAY who makes the adapter kits. It is ALWAYS best to go with a 25" lower unit with the spacer kit.

Do you know what the normal compression is on one of those engines? The dealer told me that this engine has 80-85 psi on all cylinders. I know that my 91 has 93-95 on all cylinders, but 80 sounds a bit low?

As to the Merc, I have no doubt as to the accuracy of your statement that it's advisable to go with a 25" lower unit with a spacer kit, but the engineer in me has to know why. Aren't the gears and such identical in the 20 and 25's, the only difference in them being the length of the drive shaft? What is it I'm missing?

[THEFERMANATOR]

Originally Posted by Destroyer

Do you know what the normal compression is on one of those engines? The dealer told me that this engine has 80-85 psi on all cylinders. I know that my 91 has 93-95 on all cylinders, but 80 sounds a bit low?

As to the Merc, I have no doubt as to the accuracy of your statement that it's advisable to go with a 25" lower unit with a spacer kit, but the engineer in me has to know why. Aren't the gears and such identical in the 20 and 25's, the only difference in them being the length of the drive shaft? What is it I'm missing?

The compression on the 60 degree loopers should be up around 110-125 I believe, but it can vary from year to year depending on what style porting and pistons were put in it. The problem with using the 20" lower is the driveshaft extension you have to put onto the driveshaft of the 20" lower. They can get looose and cause vibrations over time is what I was told.

[phatdaddy]

like ferm says, you want to avoid a 2 piece driveshaft if possible.

[brisboats]

Personally I hate the look of a merc V-6 with the spacer plate , so much in fact that I often swap out the midsection. 25" clean mids are easier to come by than 20" and the look especially with twins just looks "right" to me.

B

[Destroyer]

Ok, that's what I was missing.. I thought that it would use a new 1 piece driveshaft, not an extension piece on the existing 20". Makes perfect sense to me now. No way would I want a 2 part driveshaft.. sounds like it's just asking for trouble that way.

Now, the question is, which way to go... Jackplate or extension?