1972 25 HP Evinrude questions

[Justin H]

Questions....I have a 1972 25 HP Evinrude tiller with the old style sheer key prop. The exhaust comes out above the water line. Can I run a hose from the exhaust outlet down into the water? This would quiet the motor down but I was concerned about overheating.
This is my first 25 HP set up like this and it doesn't seem too have half the power of a thru the prop hub exhausted 25 HP. Have you found this to be true?
Can you rig a tell tale "P" outlet on these motors? Worries me when I can't see the "P" stream.

Thanks,
Capt. Justin

 

[jasper60103]

Re: 1972 25 HP Evinrude questions

Justin,
why would you want to muffle it? That's part of the beauty of an old outboard is that puffin and spittin sound. Anyway, the answer would be no hose because you don't want any back pressure on that port. Also, that puffin and spittin is your tell tale. I suppose you could add a pee hole though.

 

[bhughes]

Re: 1972 25 HP Evinrude questions

Yep, the water sprays out right there at the exaust. I think it might come out of the same hole.

Don't know why you would want to creat a pee hole. I think my 25hp has great power for it's size. Not sure about the difference in the prop.

 

[Rudi2]

Re: 1972 25 HP Evinrude questions

Justin,
why would you want to muffle it? That's part of the beauty of an old outboard is that puffin and spittin sound. Anyway, the answer would be no hose because you don't want any back pressure on that port. Also, that puffin and spittin is your tell tale. I suppose you could add a pee hole though.

Ah, beauty is in the eye of the beholder ;-). Seriously, enjoy your older motor the way it is. If it really bothers you, you can always trade it for a newer one.

 

[R.Johnson]

Re: 1972 25 HP Evinrude questions

Although the newer thru-hub exhaust is called a 25, it is 10 cubic inchs' bigger than your 72, beside's other changes. I have a 1975 which would be the same as your's. A friend has the newer model on nearly the same boat. There is a world of difference in alround performance.

 

[F_R]

Re: 1972 25 HP Evinrude questions

Questions....I have a 1972 25 HP Evinrude tiller with the old style sheer key prop. The exhaust comes out above the water line. Can I run a hose from the exhaust outlet down into the water? This would quiet the motor down but I was concerned about overheating.
This is my first 25 HP set up like this and it doesn't seem too have half the power of a thru the prop hub exhausted 25 HP. Have you found this to be true?
Can you rig a tell tale "P" outlet on these motors? Worries me when I can't see the "P" stream.

Thanks,
Capt. Justin

In the first place, that is only part of the exhaust. It is an exhaust relief to reduce back pressure for easy starting and good idle. Most of the exhaust goes out under water, above the prop.

In the second place, it should not be very loud, but pretty well muffled. If it is loud, the inner exhaust tube (#5) may be loose, corroded away, broken, or whatever. That tube acts as part of the muffler system as well as the tuned exhaust for good performance. A possible reason for your lack of power too.

Water blowing out the same relief port is the tell tale. You don't need another. Unless you just feel you gotta have it. Um, are you going to go all day with your head screwed around backward to watch the tell-tale?

 

[jasper60103]

Re: 1972 25 HP Evinrude questions

yea, this one don't sound loud.

http://www.youtube.com/watch?v=cJKZd9wZqrQ&feature=related

 

[Justin H]

Re: 1972 25 HP Evinrude questions

Thanks to all for your replies, you have answered all of my questions and more as usual. I just bought the old motor for $300 to use on a jon boat I keep tied up to the dock. Starts on the third pull cold and first pull warm. I will now run it with ear plugs!

Capt. Justin
Charleston, SC