1967 Johnson, Prop Swap. Help!

[Texasmark]

The heavy duty gearcase ( 1958 / 59 fat fifty ) splits along the propshaft c/line with many screws.-----The high speed gearcase had a pointy nose.------It is referred to be a " high speed " gearcase because the prop spins fast.----It is not a fast motor or racing model.

75 horses spinning a 10" prop at a 1+ gear ratio, with their "high speed" nose cone that is a magnet for collecting weeds like the rest of their lower units of the day. Best thing OMC did was to come out in '67-8-9, whatever year with their totally different lineup. I bought their 125 new in '72, 2:1 gear ratio swinging a 13+"diameter prop and had zero problems with that engine and on an 18' Caravelle tri hull, deep V and heavy. Just to see if it would do it, I was at a company picnic and got 5 skiers up simultaneously....using my regular aluminum prop...forget the pitch, but it was in the 17-19P area. It ran 39 lightly loaded with just me, I remember that because I never could get the big 40. Had no problems with that LU catching weeds. Don't ask me how long all 5 stayed up...but I got them up for a couple of minutes or so.

 

[racerone]

No ----The knowledge of the day said that a pointy nose would be faster than a blunt rounded nose.------When they started doing some real testing they found that at certain speeds in water a rounded nose would be faster and a slow spinning prop would be more efficient.----We see blunt noses on freighter ships and airliners.----We see pointy noses on fighter jets and fast hydroplanes

 

[JimS123]

75 horses spinning a 10" prop at a 1+ gear ratio, with their "high speed" nose cone that is a magnet for collecting weeds like the rest of their lower units of the day. Best thing OMC did was to come out in '67-8-9, whatever year with their totally different lineup. I bought their 125 new in '72, 2:1 gear ratio swinging a 13+"diameter prop and had zero problems with that engine and on an 18' Caravelle tri hull, deep V and heavy. Just to see if it would do it, I was at a company picnic and got 5 skiers up simultaneously....using my regular aluminum prop...forget the pitch, but it was in the 17-19P area. It ran 39 lightly loaded with just me, I remember that because I never could get the big 40. Had no problems with that LU catching weeds. Don't ask me how long all 5 stayed up...but I got them up for a couple of minutes or so.

You shouldn't tell those stories. It brings back too much nostalgia...

 

[jimmbo]

Mercury figured out the Blunt Nose back in the 50s and by the 60s had designed the basic Gearcase Shape that is stilled used today.

OMC introduced it's first Blunt Nose modern Outboard in 1966 on the 100 HP, borrowing the Gearcase from their I/O line.

When the 66 100 came out, the Speed Increase and Acceleration Improvement was greater than the 10 HP increase from the 65 90 HP would account for. It came down to better Hydrodynamics. In 68,the New Thru hub exhaust case, was introduced on the 3 cylinder 55, had it performing substantially better than the same yrs 65 hp V4, and in 69 it too was fitted to the V4s.

 

[JustWarminUp]

1976 15ft Forester Trihull,

as you had mentioned too much prop will lead to risk of damage, which I would love to avoid.

I have mounted a trolling motor (weed eating approved) I intend to use in weedy situations due to learning a lesson before with a much smaller motor... just cause they look sharp doesn't mean they make salad lol. Glad I had spare pins that day.

I will however want to go with the SS Pins.
can I reuse the main one, if it's not showing sign of stress or age. and just replace just the one that's in the end of the cone?

also I will get a measurement on that cone and confirm that's it's the larger of the 2 (my best guess)

Hate to ask because you have all giving so much help already, but could someone point me in the direction of the correct Drive pin if mine is worn/aged?


also sounds like I have come to the exact place I needed to, you guys seem to know it all lol. spot on. Plus the nostalgia sounds like a Blast!!!

 

[JimS123]

Shear pins are reusable. Marinas sell them or you can get one off ebay. Just measure it so you get the right size.

 

[Texasmark]

I hope others enjoyed this dialogue. I surely did. No doubt on going to SS on the larger engines. I never ran more than 18 hp on a shear pin driven OMC.

On the blunt nose OMC I/O I always thought that was the clumsiest looking contraption I ever saw hanging off the transom of a boat....yeah I know it was mounted to the stringers, not the transom like Mercruiser does.......and only power tilt....yeah but it tilted like 90* when Mercruiser couldn't quite get the LU out of the water with their 75.....as I recall the numbers. Do remember their 90 V4 coming out with their first blunt nosed OB. I forget what they called it.

On the bullet nose "for fast boats", the little Quicksilver racing lower unit had one but comparing that engine and it's application to a FAT 50 generation with the same idea is like eating your toothpaste. (opinion)

 

[JustWarminUp]

Sweet so all is in order!

Next
What kind of oil should I run in the gas?

I want less smoke, but smoke is always a Reassurance to me that it's got what it needs.
but everytime I fire up it's like Cheech and Chong, up in smoke lol.

anything you Senior sailors prefer over the years that would keep this motor happy and healthy for the Next 50 years?
And dont worry about if it has "This specification" or "that Specification", not like this motor has an warranty lol.

I'm after the least smoke but best protection.

 

[racerone]

See your friendly Evinrude dealer.-----They will have the best oil for your motor.

 

[jimmbo]

Or a friendly Merc Dealer, they have Excellent Oils Too!

 

[JimS123]

Over the past 55 years I have use just about all of them. As a poor teenager I used texaco 10w30 auto oil from Dad's garage. I'm not recommended that , just saying as an interesting story.

Evinrude BRP XD 50 has been an awesome product in recent years. No smoke, smooth running and cost effective. The motor hasn't blown up yet so I guess its OK.

 

[Texasmark]

Sweet so all is in order!

Next
What kind of oil should I run in the gas?

I want less smoke, but smoke is always a Reassurance to me that it's got what it needs.
but everytime I fire up it's like Cheech and Chong, up in smoke lol.

anything you Senior sailors prefer over the years that would keep this motor happy and healthy for the Next 50 years?
And dont worry about if it has "This specification" or "that Specification", not like this motor has an warranty lol.

I'm after the least smoke but best protection.

I buy my oil at wallyworld. They have Merc. and Pennzoil Premium sitting side by side and the latter is half the price. The label says it's semi-synthetic....Merc. keeps you guessing....... which seems to be the preferred mix for marine engines....some dino oil for corrosion control on log situps without running...just hearsay picked up from chatters on the rust thing. I have run 2 Merc. mid range engines using that oil and it smokes very little. With that and adding about half the recommended dose to the fuel has kept my engine's internals very clean.

 

[JustWarminUp]

So Check local dealers see what they have for Recommended product.

Ordered some Evinrude BRP XD 50 to give it a try.

Thinking I want to aim for full synth due to Age of motor and the way synthetic vs Conv targets the heat. You mention rust, is there aspects behind a marine motor and the protection required I might not know just off the top of my head? Put simply I had no clue lower units were oil filled, originally thought they were grease packed haha..

 

[jimmbo]

XD 50 is a very good oil

Don't laugh too much, I have seen some of those cases packed with Grease

You Gear case was speced for OMC Type C gear oil, mainly because that was the only Gear Oil OMC Marketed at the time. You can use either of the current BRP Oils in it, as was as the Mercury Gear Oils. There are also 3rd Party Marine Gear Oils. Don't use regular 90 weight Oil for Auto/Truck use. Marine Gear Oil's Additive Package, is engineered for Water Contamination, as well as extra EP Additives for the High Loads placed on the small gears.

 

[JustWarminUp]

I know I should start a new post, but just to be quick, lots of reading later I haven't found a definite answer.

can I use XD100?

iv found yes, no and contact dealers. Ended up with equal views in all directions. Cost aside.

figure I'll ask you guys quick due to knowing the motor.

 

[jimmbo]

A couple of Years ago, the Labels on the XD100 Bottles, said not to use it where a TCW-3 Oil was speced, maybe it wasn't designed to mix well with gasoline as it is intended to be used where Oil is Injected into the Crankcase. The more Recent Bottles no longer have that Caveat. While the XD 100 is an Excellent Oil, and is one of the Best Oils for Direct Injected Engines(FICHT, FiCHT RAM, E-tec, G2 and, OptiMax, it really is overkill for your engines Needs. When your engine was made, the Oil speced was Outboard Motor Oil, or SAE 30 non-detergent Motor Oil at 50:1. a Couple of Years Later OMC introduced their first TCW Oil. In about 85 the TCW - II Spec was released, and in the Mid - late 90s the TCW-3 Spec came about. Shortly after the First DI engines appeared and the TCW-3 Oils turned out to be inadequate for controlling Carbon Buildup in these engines. During the 2000s, there was an Anticipation of a TCW-4 Spec to cover those Engines, but it never came to be. However Evinrude and Mercury do Produce Oils that do meet/exceed those Engine's needs.XD-100 being one of them, though they say XD-50 is also usable
XD-50 is a very good Oil. Mix it 50:1 and go boating.

 

[JimS123]

I know I should start a new post, but just to be quick, lots of reading later I haven't found a definite answer.

can I use XD100?

iv found yes, no and contact dealers. Ended up with equal views in all directions. Cost aside.

figure I'll ask you guys quick due to knowing the motor.

Believe only 30% of what you read, 20% of what you hear and 10% of what dealers tell you. The good ones are retiring or dying out at an alarming rate.

Just read the label instructions.

XD100 is for oil injection motors, not for pre-mix like yours. XD50 is specifically for pre-mix.

Lots of people swear by Pennzoil in the yellow can. Based on this forum I used it in some of 2-stroke my motors, ranging in age from about 1940 to 2009. naturally, the ratio was modified to suit the age of the motor. The stuff smoked more than any old TCW3 than I ever used. The stuff is now being used in my several weed whackers.

Truth be told you can probably use any old cheep 2-stroke oil and the motor will not suffer because of it. Just depends on how much smoke you want.

Don't worry about it.

 

[JustWarminUp]

Perfect!!! XD50 it is!!

Thank you both Soo much!!! I'm working on gettin her in the water this Saturday for the first voyage. I will get some pictures to post so y'all can see

 

[Texasmark]

Or Wally World for Pennzoil TC-W3 at about $4.50 a quart. The only question is the mixing ratio. Probably 50:1 since that has been the standard for decades (1 qt oil to 12 gallons of gas) but yours may need more oil so 40:1 (1 qt of oil to 10 gallons) may be in order....I think I would go the 40 as the Penn hardly smokes in my Merc at the oil injection ratios of 80 at idle to 50 at WOT and as I said, the Penn Prem. smokes very little anyway.

I recall years ago, the big dogs on this porch (forum) discussed types of oils and the semi-synthetic was a preferred oil as it gave you the benefits of both types of oils and the dino oil seemed to control internal rusting problems better.......

Faztbullet may chime in on this as if anyone here today knows, he does.

 

[racerone]

The board room switched the mixture from 24:1 to 50:1 in 1964.-----Now most 1964 motors had exactly the same parts in 1963 model year !!