9.9 vs. 15 hp Evenrude difference

[wbeaton]

Re: 9.9 vs. 15 hp Evenrude difference

Gearcaes on 25 and 35 became same in 1981. OMC did not rate at prop in 1985 (!), the 30 has a smaller throat carb than the 35. Racers in GT-Pro class know that the 20,25,30, 35 powerheads are all the same, the 25 and 30 have smaller carb than 35, the 20 has smaller carb and also intake manifold restriction. Yes, the carb is the only difference between 25 and 35 hp OMC (I go up to 1989).

You are incorrect again. Please don't spout off misinformation as if its gospel. Go check the parts lists over at BRP before you make such claims. People depend on this forum for accurate information.

I have three 25 hp motors in my basement. A 1981, 1983 and a 1985. The 1981 and 1983 both share the same old style non-thru hub exhaust. The 1985 has the thru-hub exhaust. If fact, I bought the 1985 as a parts motor for my 1988 30 hp, which replaced my 1987 20 hp.

The carbs changed a lot in the 1980's. My 30 hp carb is not the same as the 35 hp, but then neither is the 1985 25 hp and the 1981 25 hp.

Fuel mix is 50:1. 25:1 is serious overkill.

OMC started prop rating in the mid 1980's. Not every model became prop rated in 1985.

I don't care if you are a mechanic. Means nothing to me.

 

[CATransplant]

Re: 9.9 vs. 15 hp Evenrude difference

Racing has nothing to do with it, it's about RPM and lubrication. Any OMC or Mercury running normal oil and turning over 6500 RPM needs double oil, but the new synthetic oil can be run at 50:1. Are you a mechanic? I am. I've seen the cranks on 15s after high RPM at 50:1.

Yes I am, but automotive. I have a couple of issues here. First, OMC made those 15 hp outboards for years. Most of them are still running, and on 50:1 fuelil ratio. When it comes to lubrication, I go with the manufacturer's recommendations every time.

Second, you're always talking about racing. We're not talking about racing here, except in rare situations. Mechanic or not, information that applies to racing engines has little to nothing to do with normal use.

Third, you have made numerous incorrect statements in your short stay on iboats. That's bad, because it means the person asking the question has to decide whether you're right or someone else is. That's not helpful.

Finally, go to your profile and shorten your location information. It is causing the posts to be too wide, forcing people to scroll their window to read every post in any thread you are posting in. That's annoying as the dickens.

 

[Sandhammaren05]

Re: 9.9 vs. 15 hp Evenrude difference

I'm talking about over 6500 RPM in any 1970s-1980s outboard, period. I've overhauled 15s, how many have you overhauled?

Yes I am, but automotive. I have a couple of issues here. First, OMC made those 15 hp outboards for years. Most of them are still running, and on 50:1 fuelil ratio. When it comes to lubrication, I go with the manufacturer's recommendations every time.

Second, you're always talking about racing. We're not talking about racing here, except in rare situations. Mechanic or not, information that applies to racing engines has little to nothing to do with normal use.

Third, you have made numerous incorrect statements in your short stay on iboats. That's bad, because it means the person asking the question has to decide whether you're right or someone else is. That's not helpful.

Finally, go to your profile and shorten your location information. It is causing the posts to be too wide, forcing people to scroll their window to read every post in any thread you are posting in. That's annoying as the dickens.

 

[Sandhammaren05]

Re: 9.9 vs. 15 hp Evenrude difference

Forget owners' manuals, I know the engineers who designed the motors in that era. when I had a question, i didn't go to a dealer, I called Evinrude Service in Milwaukee directly (Tom Ireland, bob Schroer). So given your misconceptions about my spreading 'misinformation', you need to become better informed.

The powerheads on your 25s and 30 will all pull 35 hp with the same carburetor, if they're in good shape. Ask the engineer who designed them (Jim Nerstrom), if you can reach him.

The OMC motors below 235 hp were not prop rated in 1985.

Nice looking ca. 1954 Johnson 10 you show, my dad's first outboard.

PS If you need some repair advice, feel free to contact me!

You are incorrect again. Please don't spout off misinformation as if its gospel. Go check the parts lists over at BRP before you make such claims. People depend on this forum for accurate information.

I have three 25 hp motors in my basement. A 1981, 1983 and a 1985. The 1981 and 1983 both share the same old style non-thru hub exhaust. The 1985 has the thru-hub exhaust. If fact, I bought the 1985 as a parts motor for my 1988 30 hp, which replaced my 1987 20 hp.

The carbs changed a lot in the 1980's. My 30 hp carb is not the same as the 35 hp, but then neither is the 1985 25 hp and the 1981 25 hp.

Fuel mix is 50:1. 25:1 is serious overkill.

OMC started prop rating in the mid 1980's. Not every model became prop rated in 1985.

I don't care if you are a mechanic. Means nothing to me.

 

[wbeaton]

Re: 9.9 vs. 15 hp Evenrude difference

No one is arguing about the powerheads. They are basically the same between the head and reed plate. Just how the extra horses are achieved is not solely by carburetor. Say what you will, but the parts lists tell a different story. I've had enough of this argument. I've said my piece. Its nothing personal. We'll just have to agree to disagree.

Thanks for the compliment. The motor in my avatar is a 1953. Its my favourite runner. A little less refined than the 1954, but I enjoy running it more.

 

[Sandhammaren05]

Re: 9.9 vs. 15 hp Evenrude difference

Where do you buy parts for the 1954 10?

Joe

No one is arguing about the powerheads. They are basically the same between the head and reed plate. Just how the extra horses are achieved is not solely by carburetor. Say what you will, but the parts lists tell a different story. I've had enough of this argument. I've said my piece. Its nothing personal. We'll just have to agree to disagree.

Thanks for the compliment. The motor in my avatar is a 1953. Its my favourite runner. A little less refined than the 1954, but I enjoy running it more.

 

[CATransplant]

Re: 9.9 vs. 15 hp Evenrude difference

I'm talking about over 6500 RPM in any 1970s-1980s outboard, period. I've overhauled 15s, how many have you overhauled?

I'm not going to get into a long argument with you. I'm done with this thread. Now, will you go to the User CP and delete all that text in your location or not? It's annoying as the dickens to have to scroll to see the posts in these threads, and your location information makes every message in every thread you post in wider than the screen.

Suffice it to say that we're not impressed with your name-dropping, your racing experience, or your opinions regarding what oil to use and how much. Whatever experience you may have is outweighed by that of others on this forum.

We're a friendly bunch, but not too tolerant of people who think they know it all. Just a word to the wise.

Now, go fix your location information so everyone doesn't have to deal with your message width, please.

 

[Sandhammaren05]

Re: 9.9 vs. 15 hp Evenrude difference

Actually, I have no interest in 'impressing' anyone. I have a lot of experience with motor repair, boat set up, prop modifications, and more, and am willing to share it. The only information of use provided by you was that my location line is too long. Now, go fire up that Sea King and take a ride.

I'm not going to get into a long argument with you. I'm done with this thread. Now, will you go to the User CP and delete all that text in your location or not? It's annoying as the dickens to have to scroll to see the posts in these threads, and your location information makes every message in every thread you post in wider than the screen.

Suffice it to say that we're not impressed with your name-dropping, your racing experience, or your opinions regarding what oil to use and how much. Whatever experience you may have is outweighed by that of others on this forum.

We're a friendly bunch, but not too tolerant of people who think they know it all. Just a word to the wise.

Now, go fix your location information so everyone doesn't have to deal with your message width, please.

 

[VivaLaMigra]

Carburetor is MAJOR difference. There are also reed valve shims on later 15's, and tuned exhaust on some after '81 through I think they discontinued that and went to a bigger bore to get the rated HP at the prop shaft. In any event you can't see the carb throat when the carb is installed since it's down beside the recoil starter - you have no direct view into it.

 

[racerone]

This argument is 10 tears old---------BOOM

 

[GA_Boater]

Carburetor is MAJOR difference. There are also reed valve shims on later 15's, and tuned exhaust on some after '81 through I think they discontinued that and went to a bigger bore to get the rated HP at the prop shaft. In any event you can't see the carb throat when the carb is installed since it's down beside the recoil starter - you have no direct view into it.

Will you please stop posting in old threads!