Johnson vs Mercury - Technology Question

[Texasmark]

Re: Johnson vs Mercury - Technology Question

Have enjoyed following along your dialogue guys. Very interesting as I now find history interesting......but when I was in school.....yucko!

Chris, what do you mean when you say the fat 50 is/was a pulling machine?

On the Yammie similarities, if you go to the Yammie site and read up on the company history, the CEO of the company decided to get into the OB business and the way he did it was to go out and see what others were doing..since he was entering the market late, was no time for errors...makes sense. Looks like he looked too closely at the competetion d. We had the same problem when I was working.....had to be careful who you let into the plant and had to watch them the whole time they were there....except they could go to men's room on their own. d .....had to add that....chuckle chuckle.

I had one of those 85 4 cyls (cowl was black with blue and red stripes on the decals and Merc was spelled with a small m. ....somewhere in the early '80 era). My '02 3 cyl 90 runs out a lot better (faster....like 10 mph on a fairly similar boat) but the 4 cyl was a lot smoother idling.

Had one of those 115 last model towers. Loved it in spite of a couple of annoyances.
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Shifting mechanisms
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Gonna bet my clutch dog rattle is caused by the design of the Merc shifter. Having a cam, it has a spring that puts pressure on the shift dog. Since there is a spring it can yield to pressure and at idle rpm's where we have the problems I am about convinced that the spring is the cause.

You guys are batting around shifting philosophies, but I'd bet the OMC doesn't suffer from rattle cause I don't think it has a spring.......does it?

And back to history, I can't believe the shenannigans Merc pulled before it finally decided it needed a shift mechanism FNR. Can't believe that late in the game you had to stop the engine and restart it to shift into reverse.

Thanks again for the historical review.

Mark

 

[Chris1956]

Re: Johnson vs Mercury - Technology Question

Mark, That Fat-Fifty was a 70.7 cubin inch 4 cylinder monster. The carb (at least the one I had) would dump 1/6 of its fuel oveboard directly from the intake manifold to the water jacket. It did idle smooth however. It also pulled real strong from lower RPMs. It would "pop" a boat onto plane real quick. They never really revved up much, but you could stay on plane a low speed due to the power available at low RPM. When you pulled a skiier, the skiier could cut hard, and slow the boat down a lot, but the RPM of the motor didn't change. I once lost my Fat-Fifty into the salt water, while it was running. It took me nearly three days to find it. I stripped it down, cleaned out the sea shells and weeds from the crankcase, connected some fresh gas and fired it up. The "drowning" didn't seem to phase it. Most motors would never have worked again, that one didn't mind.

OMC did a publicity stunt in the sixties, where they installed 2 Fat-Fiftys on a 23 foot boat and crossed the ocean with it. A barge went along carrying the 1500 gallons of fuel necessary to make the trip.

 

[Texasmark]

Re: Johnson vs Mercury - Technology Question

d d d Hear you on the gas and know you are telling it like it was.

So Chris, you just hit upon part of my torque questions elsewhere (HP vs rpm's).

Here is a 70 cu inch 4 cyl engine rated for 50 hp that is twice the size of their 2 cyl 40 hp. It swings a large diameter (13") 3 bladed prop with a 2:1 gearbox, at low rpms (4500). Man if that isn't torque personified, I know not what is. No wonder it could get cabin cruisers full of folks on plane in a hurry.

So along comes a 90 hp Yammie (of today) at 70 cu in, 2:1 gearbox, about the same rpm's. Now what are you going to push with that? (Not criticizing Yammie, just trying to understand what it can do.)

The torque confusion continues thru OMC's later years where they up the hp to 75, up the cubes to 90, which should maintain the torque but now they have it connected to a 1:1 (sorta) gearbox swinging a 10" dia wheel.........that's the same dia they had on their old 35's.

Talking about being confused.....I certainly am.

Mark

 

[jimmbo]

Re: Johnson vs Mercury - Technology Question

Tex..
The prop on the post 1959 70.7 and 89.5(except 100hp models) inch blocks was actually smaller than the props on the the 25, 30, 35 and 40hp models in the 50s and 60s. The actual ratio, as mentioned before was 23:20, the props were 10 3/8 x 10 (std); 10 x 12; 10 x 11; 10 x 9 1/4; and 9 1/2 x 10.

 

[Texasmark]

Re: Johnson vs Mercury - Technology Question

Well, that's my point. Here is the company that championed large cubes and low rpms on a reasonably large prop and lo and behold, they up and do that.

I only ran one of those rigs once. I was looking at buying a used 16' MFG boat with a 75 on it running one of those high gear ratio's and dinky props. The boat was lightly loaded (just me and gas) and it took off and scooted right along. Have no idea as to the numbers I was running at the time. Also don't know what would have happened had the boat been loaded.

Must have been successful as they kept the idea for several years.............till their 3 cyl looper changed everything, including lower units. d

Mark

 

[gotbait]

Re: Johnson vs Mercury - Technology Question

All of you guys know much more about engines than I. Heres my question. I find a boat I like. I go to check it out and everything is good. Should I care if there is a Johnson or a Mercury straped to the back?

 

[jimmbo]

Re: Johnson vs Mercury - Technology Question

Six with one, half a dozen with the other. Find a dealer you trust and buy what he sells. Overall both are fine engine lines. If they weren't they would have been out of business long ago. Each brand will have loyalists. I've owned both and like I said before, I think Mercury was way ahead in the 60s. These days... I would give Evinrude the nod because of the E-Tec engines. Mercury has the Verado line and it has good reveiwsas well, but I love 2 strokes.

Tex...

My dad, my uncle, and I all had 1965 90hp motors with the tiny props. They seemed to be able to carry a load, maybe they had such high slippage to begin with that a bit more wasn't noticable. I do know that my later 90hp Merc could have pulled either backwards and still have more top speed.

 

[fishdog4449]

Re: Johnson vs Mercury - Technology Question

I believe the best motors were made in the 70s and 80s, that was when quality was valued more than quantity or price.
I believe in the saying that a Merc will get you there fast, an Evinrude will get you back. Alas, fate has dealt me mostly Mercury motors so far and while I don't like them as well as E/J, they do run great when they run.