Curiosity Finally Gets the Best of Me!

[racerone]

Friends had a 17' boat with the 66 model 100 there were weekends when that motor hardly cooled off.---Had 3 gas tanks 6 US gallons.-------A fine piece of machinery.-------I had a motor once with the pointy electric shift.-----Installed the big round nosed 100 gearcase and speed went from 45 to 49 MPH with no other changes to the motor.-----Modified V-4 that ran at over 6000 RPM.-----I could not find or afford a higher pitch prop at the time.

 

[Texasmark]

But the EARLY 2 piece JOHNSON / EVINRUDE gearcases were ultra precision made ! -------Say on a 1968 model 40 HP you could install new gears and bearings without needing special tools or time to shim the gears.-------Many folks do NOT see that concept .-----Just my opinion I guess.

That is certainly a good point and I agree....if you are lucky with the gasket.

 

[Texasmark]

But folks look at the pointy gearcase and think-----" that must be fast "-------Nature will fool you and as you said the pointy lower unit was NOT faster.-----The 100 HP model 66 / 67 / 68 electramatic was big / round nosed and FASTER.

My 125 had the electric shifter but not the bullet LU and I know the one of which you refer. On the gasket I'm talking about on the early vintage, 1950 give or take time line engines. Never had a problem with my 125 and that would have been my only reference to their one piece LU that came out on the "Triump" 55.

 

[Texasmark]

The 1st State of the Art Gearcase OMC made, would have been the 1968 55hp. I came from an OMC family, where Mercs were looked down on, and referred to as 'Screaming Mercs". So when I bought an Inline 6 in 84, I was a Heretic. But I found it to be a very good engine. In Hindsight, Mercury did have some much more advanced engineering(gearcases and props) than OMC during the 60s, by 1970 OMC caught up, but when the V6s were introduced, Mercury once again pulled ahead.

I do concur with Racer about the OMC Cases were able to be slapped together without shimming. But the Hydrodynamics weren't the best, especially the design they used on the V4s from 1960 thru 1968, the100 HP excluded

I thought the 90, forget the acronym, which may have been built into the 100 to which you refer in later years had a beast of a LU. Been a long time but that is my recollection.

While we are beating up on LUs, I restored a 1965 Merc. 110 IO and part of that was getting the spanner nut off/out so that the prop shaft and bearing carrier could be removed, without tearing up the casting. The boat was a Starcraft 18' Holiday, freshwater boat and over 10 years old and I had a bear of a time getting it out. Cannot imagine being a Merc marine tech in Miami or such place and having to deal with such in a salt water environment.

 

[racerone]

Most folks developed the technique of cutting that nut out on Mercury motors.----Cheaper than struggling .----Time is money.------Not sure how / why you would struggle with the gasket on 1950 OMC lower units.

 

[jimmbo]

1965 90 hp

1966 - 68 100hp gearcase

 

[racerone]

Yes that is the electric shift / fast turning / small prop.----Good acceleration put poor top end.-----The big 100 HP unit will fit on those as well.-----And jet liners do not use a pointy nose.----They sure would if airlines knew a pointy nose saves fuel.------Jet fighters do use pointy noses because of higher air speeds.---Cruise ships use round noses as it is more eficient at low speeds in water.-----Nature will fool you sometimes.

 

[jimmbo]

I wouldn't say the puny gearcase had very good Acceleration. Our 90 hp was freshly rebuilt and we ran two props on it, the 10 X 11, which gave us 4400 rpm, and the 10 X 9 1/4(lowest offered) which did 4800 rpm. We ended up leaving the 9 1/4 on. The bigger 100 case was better at Holeshot and Top Speed.
Large Ballistic Missles have a Blunt/Rounded Nose, and they travel faster than any Aircraft. Fluid Dynamics in place there

 

[flyingscott]

I think we can all agree that if you put the simple OMC powerhead on a Mercury lower unit , that would have been quite a motor. Oh wait, Yamaha did that never mind.

 

[Texasmark]

Most folks developed the technique of cutting that nut out on Mercury motors.----Cheaper than struggling .----Time is money.------Not sure how / why you would struggle with the gasket on 1950 OMC lower units.

Probably because I was a teen and lacked experience and tools.