1971 50 HP Johnson "Won't Open Up" at Full Throttle

[E_S_A_D]

We just picked up a boat, 1971, today and took it for our first trip. We at first thought we couldn't get it to start. Turns out, the spark plug wasn't connected to the wire. Whoops.

So, we tried that and connected it. Worked fine; however, we noticed it would slightly make a stuttering motion/ sound while running. It never would open up fully at full throttle either. It would top out at about 22 mph, which should be more around 30. It sounded like it wanted to engage, but it wouldn't.

What could this be? Should we get new plugs, premium fuel? Any ideas??? Thanks! It hasn't been run, until today, besides in a driveway for over a year.

thanks again

Edit- Also, I noticed that this engine doesn't have the cooling 'stream'. Instead it comes out of a gap on the back of the engine in a 'dumping manner'. Basically just falls out back into the water. Is this correct?

 

[sloopjimd]

Re: 1971 50 HP Johnson "Won't Open Up" at Full Throttle

First about the water which is the easiest of the 2 questions. In 71 there wasnt a tell tail (pee tube) so water will come out the 1 or 2 exhuast wholes in the leg of the motor.
What size boat is it fiberglass or aluminum? these things will matter. You dont say if the motor seems like it is bogging down or running ok.
I had a 16 foot trihull with a 50 and 22 knots was about all it would do and i rebuilt the entire motor including the carbs.
You could rebuild the carbs and do a sync n lync get a good book (clymer)

after reading your post again it could be that you have a base gasket leak which would explain alot. If water is coming out around the base of the power head then theres your trouble.