Merc 'Tower of Power' differences? Need help please

[Boxermachine]

I have a 1987 115hp unit with a dead, no compression 3rd cylinder. I have an opportunity to buy a late 70's power head that is good to go, however it had a distributor system, which unfortunately, does not come with it. Question, is it compatible with my newer, non distributor set-up? Will my ignition bolt up, or are they two different animals? Thanks in advance! Chris

 

[wired247]

Re: Merc 'Tower of Power' differences? Need help please

Two different animals. You can swap the whole powerhead but ignition and all stuff is different and doesnt interchange. Many internal parts are the same but the block and ignition are not among those.

 

[Boxermachine]

Re: Merc 'Tower of Power' differences? Need help please

Thanks, I was hoping that wasn't the answer. Next question, can I swap out the crank and pistons with the older one to repair mine? When cyl 3 goes down,(seems common) will just a crank/piston swap do the job? Thanks again!! Chris

 

[wired247]

Re: Merc 'Tower of Power' differences? Need help please

Depends how bad you burned up #3. Sure, conceivably you could swap parts but earlier 115 parts are not the same as later 115 parts . Think of your 115 as a low compression 150. They changed rating systems at the same time they reduced compression so its a little muddled. It has pistons like the earlier 1500 that work with the recesses in the block to create kind of a half *** looper effect. The 70's 115's with distributors are what later got called 90's and dont have the pistons that make the ported blocks work the way they were designed. Yes, you can use non ported pistons in the ported blocks but you will lose a lot of power doing it. .

 

[Boxermachine]

Re: Merc 'Tower of Power' differences? Need help please

Thanks again. Back to square one. I am looking for a 'cheap' fix, but so far it doesn't seem possible. I'm going to keep searching for an interchangeable powerhead. Thanks again for your advice. You saved me from a giant headache!!!
Chris

 

[wired247]

Re: Merc 'Tower of Power' differences? Need help please

Why not just hone the bore out if its not too bad and replace the one piston? Your'e out some rings and gaskets and a piston. You also get to experience the joy that is assembling an inline.