1977 Johnson 70 hp needs new power head....

[CODY A]

So after a lot of tinkering, I finally took my motor into a mechanic I have used for years and trust. The motor would idle fine, but when given full throttle, it just wouldn't pick up speed, like it had no power. Would only go about 10 mph. Btw this is on a 16 ft fiberglass v hull. All 3 cylinders were firing, spark was good, I rebuilt the carbs, put a new 15x13.75 prop on it, and it helped, but still would only go maybe 12 mph. I took it to him, first test he did was a compression leak test, and turns out the cylinders are leaking around 60% compression. Rings are fried :-/ mechanic says it needs a power head replacement, and it would cost around 900-1000 bucks. My question.....Is it worth it to rebuild this one and know what is in it, or look for a new outboard? My boat has a 105 hp limit. Thanks for any input.

 

[CODY A]

Also, im not wanting to spend more than about 1500 on this motor or any motor. What thinks you guys?

 

[MTboatguy]

This my opinion, I would start looking for another motor, that motor is 38 years old and for the money you would put into it, you can find another one in better shape. We have all chased a motor with a problem, but as I get older, I have figured out, sometimes it is best to cut and run, so I can get on the water quicker, and start kicking back drinking a beer and drowning a worm or two.

 

[CODY A]

Ok, and I guess my next question is, if I did go shopping for a new motor, what do you think is about a best/some of the better options for my boat and budget? I found a 1991 mercury 90 hp that was just serviced at buckboard marina (I live in Wyoming, near flaming gorge) for 1500. Just wondering where I should start. This is frustrating ha ha.

 

[emdsapmgr]

FYI. That 77 3 cylinder only has 49 cubic inches. It's pretty puny for that kind of hp output. The late 80's or early 90's it grew to 56 cubes, a much better engine.