Repowering with 1970s-1980s 100-125HP -- any gotchas ?

calvinator

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Sep 22, 2010
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Hi all -

I want to repower my 1980s pontoon with a 100-125HP motor. Pontoon is rated to handle that.

I really have simple needs, so a much newer high priced engine is not what I'm looking for.

I'm drawn to the 1970s and 1980s motors because of price. My intent would be to buy a water ready one. There are some local outboard rebuilders in town and the marinas get used stuff too. I would buy one that has some known history and checks out well.


Probably buy a Johnson, Evinrude, Mercury. Anything in those 1970s-1980s brands to stay away from ? I see a lot of the "Tower of Powers" -- are those desirable ?

I also see some Suzukis and Marniers too. Good stuff?


THANKS
 

JB

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Re: Repowering with 1970s-1980s 100-125HP -- any gotchas ?

In that power range and that year range I think I like the JohnnyRude 60 degree loopers best.
 

Willyclay

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Re: Repowering with 1970s-1980s 100-125HP -- any gotchas ?

Anything in those 1970s-1980s brands to stay away from ?

Evinrude/Johnson V-4 and V-6 models prior to 1978 used hydraulic shift gearcases and electric/hydraulic versions in the early 1970's. Might be something to avoid to keep your life simpler from a parts and service angle even if the motor you find is working perfectly. Good luck!

EDIT: OMC V-6 motors continued to use hydraulic shift gearcases through 1978.
 
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Chris1956

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Re: Repowering with 1970s-1980s 100-125HP -- any gotchas ?

60* loopers were not avail from Johnnyrude, in that time frame. The 90*V4 Johnnyrudes were real good motors. You should be able to get HP from 90 - 140. Merc inline motors are fine from late 70s on, when they changed over to the ADI igniton. Watch out for salt water used Mercs, as the exhaust baffles and covers can rot thru.
BTW - motors from the 80s outght to be real cheap, like $500 and less.
 

steelespike

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Re: Repowering with 1970s-1980s 100-125HP -- any gotchas ?

I've got a few boating years under my belt. About 63 years.
As the years have passed outboards have gotten progressively more efficient.
Our 67 40 Evinrude was kind of thirsty Our 77 50 Merc was noticeably better.
Then our 88 50 Evinrude was noticeably better than that.Can't tell you exactly where the various improvements came about
But its fairly obvious newer the better for efficiency.I feel that E/J parts are a little more readily available.
While properly cared for electric/hydraulic shift E/J motors work ok I think your better off with conventional
gear case. Todays shifting is essentially the same as it was around 1949.Not particularly sophisticated but well proven.
Another point around 85 motors became rated at the prop,were rated at the crank previously.
 

ondarvr

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Re: Repowering with 1970s-1980s 100-125HP -- any gotchas ?

Evinrude/Johnson models prior to 1978 used hydraulic shift gearcases and electric/hydraulic versions in the early 1970's. Might be something to avoid to keep your life simpler from a parts and service angle even if the motor you find is working perfectly. Good luck!

All of my 1975 and newer J/Es had mechanical shifting, not the unwanted electric or hydaulic systems. I don't know what the end date was for those models.
 

steelespike

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Re: Repowering with 1970s-1980s 100-125HP -- any gotchas ?

I think the Electric/hydraulic shift dates to the early 60s early were electric later Hydraulic I believe the manual shift was built at the same time. At a glance the later mechanical and hydraulic models were similar looking.
 

Bob_VT

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Re: Repowering with 1970s-1980s 100-125HP -- any gotchas ?

The V-4's are very reliable and IF you can get a Post 1984 V-4 .....they are HP rated at the prop........ Pre 1984 are powerhead rated HP. The 1984 and later V-4's will beat an older one of equal "advertised" HP.

Tower of Power inline mercs/mariners have higher then normal problems (at least more maintenance) due to an extra carb

What are you running now?
 

coolbri70

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Re: Repowering with 1970s-1980s 100-125HP -- any gotchas ?

I have no experience with the mercurys, i have a 79 evinrude v4 crossflow, probably the most reliable engine i have, i never wonder if it will start. one thing negitive, she's a thirsty girl.
 

calvinator

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Re: Repowering with 1970s-1980s 100-125HP -- any gotchas ?

The V-4's are very reliable and IF you can get a Post 1984 V-4 .....they are HP rated at the prop........ Pre 1984 are powerhead rated HP. The 1984 and later V-4's will beat an older one of equal "advertised" HP.

Tower of Power inline mercs/mariners have higher then normal problems (at least more maintenance) due to an extra carb

What are you running now?

On the toon now is a 1989 Mariner 60. It moves the toon 10-12MPH.

Would like a 115 or 125 motor so I can see 18MPH.
 

trendsetter240

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Re: Repowering with 1970s-1980s 100-125HP -- any gotchas ?

If I were you I would look somewhere in between the 70's / 80's motors and the new expensive ones. The 1990 through 1998 Johnson and Evinrude motors are far better (in my opinion) than the 70/80 models. That extra 10 to 20 years of wear on the older motors will show in the most annoying areas such as power trim and tilt, electrical, fuel lines, bolts that are rusting etc.

The 3 cylinder J/E from the early 90's are my favorite motor. I'm sure a 70hp from that timeframe would be better than the current mariner but maybe not enough of an improvement for you. The v4 looper 115hp will be an absolute night and day difference from the current 60hp. But, the older crossflows will suck the gas and new loopers will be slightly more expensive.

Don't know your budget but I highly recommend a 1990-1998 v4 115 Johnson / Evinrude if you want to go faster. A 1990-1998 70hp if you want to save on upfront cost, maintenance and fuel.
 

Chris1956

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Mar 25, 2004
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Re: Repowering with 1970s-1980s 100-125HP -- any gotchas ?

I presume that 'toon is heavy for the torque of that Mariner. If you want to stick with the 80 models, try a Johnnyrude V4. They will have the best low end power. The Mercs had real good mid-range power, but that is not what I think you need.
 
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