58 Johnson Fuel Mixture

"I have converted the two line

"I have converted the two line pressurized system to a single line (61 by pass-cover plate w/fuel pump. All of that works well. Since this is to be a trolling motor, my intentions were to use the same deliver line for both motors. I had asked if the 58 could be run on 50:1 and I thought the answer was yes. However, in doing a search for that info, I drew a blank. I guess this is the long way around to apologizing for asking yet another fuel mixture question (almost as ubiquitous as "what year is my motor?").

Does this '58 18 hp Johnson have needle bearings and can it be run safely on 50:1 mix?"

"Run it on 40:1, oil is cheap,

"Run it on 40:1, oil is cheap, engines are not. Plus you will not foul your plugs, I have not and I have been running like this for years. I have a 1957 Johnson 18hp. After running it for a while, put your hand on the flywheel, if it is hot, increase the fuel-oil mix. Jon"

"Jon, a spinning flywheel is a

"Jon, a spinning flywheel is air cooled why would it get hot?And yes the 58 18hp has needle bearings."

"Even though heat is transfere

"Even though heat is transfered to the air from the flywheel via convection, the head conducted from the friction on the crank (due to lack of lube) to the flywheel will be much greater causing the flywheel to be hot, eventually causing the coils to break down the the motor to shut down. I have had this happen on my 62 40hp Johnson."

"Late last year I had asked th

"Late last year I had asked this question and due to my poor search skills I have not been able to retrieve Joe Reeves answer. My recollection was that the 58 18 hp Johnson had needle bearings and should operate properly on 50:1 mix. but having heard differing opinions lately, I just needed to be set straight because thing baby is going into the water this weekend!"

"Larry,
Run it on 40:1,

"Larry,
Run it on 40:1, trust me on this one. More oil will NOT hurt your motor, it will actually keep the cylinders from scoring. These motors were designed to run on 24:1 gas-oil mix until 1964 when they changed it to 50:1, but the 18hp can run on a 24:1 and be perfectly fine, even with modern oils. It will protect the internals better and you will not foul a plug. Lets put it this way, I have been working on OMC outboards made from 1930's to 1960's and I have rarely had a motor foul a plug because of too much oil. You are not saving much oil moving from 40:1 to 50:1, and oil is cheap, a gallon is 8 dollars at Wal-Mart. If you are even the slightest bit concerned about fouling a plug, go spend 4 dollars and pick up two plugs, place them in the boat just incase anyting ever does happen. I always carry a crescent wrench, flat head screw driver, and two sparkplugs, and I have NEVER been left on the water (Knock on wood). Jon"

"Joe,

I'm trying to wra

"Joe,

I'm trying to wrap my brain around your reply. You advocate a 40:1 mix as opposed to the original 24:1 mix specified in 1958. Why did you go to 40:1?"

"Larry,
The 40:1 mix is u

"Larry,
The 40:1 mix is used because the motor can be run on 50:1 with the new TCW-III oil, BUT I do not run any motor that asks for 50:1 on 50:1 because you are flirting with a greater chance for premature engine wear. I always run motors that ask for 50:1 on 40:1 since I have seen too many motors with severely scored cylinder walls and warn bearings due to lack of oil. You can use the 24:1 mix on your engine, it will just smoke a little bit more, but it will not hurt it. I use a 24:1 mix when I winterize my 57' 18hp because it does a really good job lubing the internals. Its your choice, some people will say its fine to use 50:1, and you will probably be fine, I like to say on the safe side and use a 40:1 mix. Jon"

"Jon, I understand.

My reas

"Jon, I understand.

My reason for converting to a single fuel line and a fuel pump with a 50:1 mix on this motor is to use it as a trolling motor and draw from a single fuel source."

"Larry,
You can run your

"Larry,
You can run your big motor on a leaner mix too, it will not hurt it, even 45:1 would be fine, just keep it richer than 50:1. Jon"