1973 Johnson 85

[jbatten]

I am looking at buying a 1973 Boston Whaler that has the original 1973 Johnson 85 HP engine. The boat is perfect but my concern is with the engine. This boat has been in the same family since it was purchased new in 1974. The second owner is the brother-in-law of the original purchaser. The second owner has had it for 4 years and barely used it, hence the sale. I would have to assume that the motor has been taken care of as well as the boat has.

All 4 cylinders have compression between 116 and 121. My concern is how strong can the motor be @ 33 years old. There is no hour meter so it is impossibe to tell how much use it has received.

Any thoughts on purchasing a motor that is 33 years old?

 

[JB]

Re: 1973 Johnson 85

It's only 33, jbatten. For a well maintained outboard that is not old.

There are many, many Johnson engines older than that in regular service and delivering full performance that have never been torn down.

With compressions over 110psi and within 5% span I would say that she is ready to purr for another 33 years.

Good luck, and welcome to iboats.

 

[DJ]

Re: 1973 Johnson 85

The '73' 85 was one of the best outboards ever built. It shares little with the 99.6 cid" blocks that the 115 and 135, of that year, offered.

The 99.6 cid block went on, into the nineties, as OMC's offering. But the 96.9 cid block of the the '73'-85 was a good one.

Do this.

1. By a generic manual, here on iboats, for about $30.00. I prefer-Seloc.

2. Rebuild the carbs with new OMC/Bombardier kits-a dealer item.

3. Replace the water pump with new parts of the same origin.

By the way, the V-4 is easy easy to access the shift rod (water puimp replacement) while the carb's are off.

Do all that, about $200.00 (outside) and you'll have an engine that will outrun/outlast you.

The "Whaler" with that engine is a great package. Super performance and it will get decent economy if you prop it right.

Prop it to turn 5500-5700 at Wide open throttle.

If the boat looks good-BUY IT. That's a NICE rig.

Use TCW-3 oil-ONLY @50:1 and Champion plugs ONLY!

That engine came with surface gap Champions. UL 77V, as I recall. Use electrode type Champions (equivelant) at .040" gap and it will idle nicely.

We'll be here, for questions.

 

[tschamp20]

Re: 1973 Johnson 85

you give great thorough answers djohns. where were you 2 weeks ago?
i read somewhere .030 for the gap which is what im using w/ my autolite 2634.i do notice a slight erraticness about the idle,would increasing gap help this?
sorry for the thread hijack,thought it would be relivant for both of us.
doug

 

[DJ]

Re: 1973 Johnson 85

tschamp,

I was on vacation burning many hydrocarbons through many Johsnons/Evinrudes and a MerCruiser 454.

That last gives me shivers.

Get the Autolites out of that engine. Go back to Champ's.

It has been discovered, in later years, that the .040" gap helps the idle-a bit.

Be aware:

1. The wider gap will only help "detonate" an engine that has clogged high speed jets.

2. Water pump efficiency is paramount, regardless, of the gap.

I love that engine. I spent countless hours behind one on a Starcraft Super Sport, as a teen. We'd run 18 gallons of gas through it, in 6 hours. Trust me, I know that engine.

Maintain it, according to the book, and it will run forever.

If it has the "original" OMC tilt/trim unit, they can be finicky. The engine is worth putting on a CMC unit if the original TNT fails.

 

[tschamp20]

Re: 1973 Johnson 85

what model # for champion?

 

[DJ]

Re: 1973 Johnson 85

tschamp,

Don't quote me, for I do not have a Champ. catalog.

I "believe" they would be Ul77JC4, or equivelant "new" Champ. number.

Enjoy the '85', it's a sweetheart.

I just re-read your post. Thought it was an 85?

The 115 is a bit of a a different animal. Still runs nice, but not as sweet as an 85. The 115 can be made to idle nicely, also, with regular (non surface gap) plugs. Again, Champs's only.

Same gap-.040".

 

[jbatten]

Re: 1973 Johnson 85

It's only 33, jbatten. For a well maintained outboard that is not old.

There are many, many Johnson engines older than that in regular service and delivering full performance that have never been torn down.

With compressions over 110psi and within 5% span I would say that she is ready to purr for another 33 years.

Good luck, and welcome to iboats.

Thanks for all the great feedback. It is a great rig and is now parked in my garage in Galveston!

 

[jbatten]

Re: 1973 Johnson 85

The '73' 85 was one of the best outboards ever built. It shares little with the 99.6 cid" blocks that the 115 and 135, of that year, offered.

The 99.6 cid block went on, into the nineties, as OMC's offering. But the 96.9 cid block of the the '73'-85 was a good one.

Do this.

1. By a generic manual, here on iboats, for about $30.00. I prefer-Seloc.

2. Rebuild the carbs with new OMC/Bombardier kits-a dealer item.

3. Replace the water pump with new parts of the same origin.

By the way, the V-4 is easy easy to access the shift rod (water puimp replacement) while the carb's are off.

Do all that, about $200.00 (outside) and you'll have an engine that will outrun/outlast you.

The "Whaler" with that engine is a great package. Super performance and it will get decent economy if you prop it right.

Prop it to turn 5500-5700 at Wide open throttle.

If the boat looks good-BUY IT. That's a NICE rig.

Use TCW-3 oil-ONLY @50:1 and Champion plugs ONLY!

That engine came with surface gap Champions. UL 77V, as I recall. Use electrode type Champions (equivelant) at .040" gap and it will idle nicely.

We'll be here, for questions.