swapping power head on a 78 70hp merc - should I try it?

[suzukidave]

Hi folks, so I am wondering if anyone can give advice on what's involved in swapping powerheads on a 78 70hp. I bought a boat with a bonus seized motor that supposedly died as a result of sitting for 6 years. No way do I have time to rebuild it. <br /><br />I am a very amateur mechanic but I have tools and am willing to read a manual. I guess I am wondering how much time a swap will take me and whether I am crazy to try. Also, what else do you normally do at the same time? I am thinking I will rebuild the carbs, replace all the wires and ground cables, replace the fuel lines, and rebuild the fuel pump. <br /><br />Also, I notice iboats offers power heads from two mancufacturers with a price difference of $500. What is the difference, if any, between them?

 

[phatmanmike]

Re: swapping power head on a 78 70hp merc - should I try it?

try it, be brave

 

[Fishin4fun]

Re: swapping power head on a 78 70hp merc - should I try it?

what is the motor that has a seized powerhead?<br />year hp?

 

[suzukidave]

Re: swapping power head on a 78 70hp merc - should I try it?

As per the title of the thread, it is a 1978 70hp mercury.

 

[Fishin4fun]

Re: swapping power head on a 78 70hp merc - should I try it?

If both of them are 1978's and both 70's go for it, it is a very very simple swap will take a couple of hours is all. Just have to disconnect your throttle, and gear cables, and your power cable, then take off the mounting nuts and the powerhead popps right off with a lift. Get a new gasket, and bolt her back up. If you can re-string a fishing rod, you can do this swap. Too easy!

 

[suzukidave]

Re: swapping power head on a 78 70hp merc - should I try it?

thanks fish4fun. I am thinking of buying a powerhead off an aftermarket supplied and swapping mine back as a core so I assume I would also have to strip a lot of stuff off the old powerhead and put it on the new one, but if the basic install is just dropping it onto the drive shaft that helps me visualize it..

 

[Chris1956]

Re: swapping power head on a 78 70hp merc - should I try it?

Dave, I did the powerhead swap last February. (The rebuilt powerhead came from Iboats) The rebuilt powerhead came with less parts than I had anticipated. I had expected to reuse carbs, stator, distributor etc, however there were some surprizes. For example, the rebuild came without carb mounting studs and block mounting studs. I needed a pipe wrench to remove my old ones and installed them with marine-tex. In addition, the rebuilder recommended new water tube seals, and exhaust extention gaskets. This of course turned into new motor mounts, due to corrosion issues. Also I cleaned the carbs, rebuilt the fuel pump and put in new spark plug wites. It ended up taking longer than I anticipated. I recommend you get a manual, since you will likely need it.

 

[KCLOST]

Re: swapping power head on a 78 70hp merc - should I try it?

Yea, you have to remember that a powerhead may or may not have all the other stuff you need...<br /><br />Pistons, rods, etc... Make sure...