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1956 johnson 3 hp won’t fire

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Rambo58

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I am working on a 1956 johnson 3 hp. Motor did not fire when I got it. Took flywheel off checked ignition parts all look good. I did take plug wires off bottom of coils and trimmed off an inch of wire and put them back on coils. Now I have lower cylinder fire but top cylinder has nothing. Curious on thoughts of what I need to look for to solve the issue. Thanks
 
The only way to clean the points is to replace them with new condensers at the same time. Can you wigglethe points plate up and down? What color are the coils? If they are black or dark blue teplace them as well. They will fail. Did you pull the coils to install the plug wires? Air gap to the flywheel magnet is critical hold a straight edge so the laninate is square with the bosses they are mounted on. Point gap is a field adjustment to get you home the best way is with a toming light. On the outer edge is two marks on the points plate shine the light at the marks and the mark on the flywheel needs to inbetween the two marks on the plate. Your flywheel has the access hole to adjust the points. Clean the points good with acetone same as the feeler gauges. Once you get it timed properly and engine sync set it should be a one pull start engine. Be sure and torque the glywheel to spec before starting it.
 
Take the points apart and inspect them and if not mechanically worn, degrease them with brake cleaner, then individually polish each contact shiny bright with 400 grit wet-or-dry sandpaper. Reassemble and set gap to 0.020" at the high point of the cam. Of course if they are worn, replace them. Note: Either way, you have to take them apart, whether to clean or replace them.
 
Rambo58 said:
Any recommendations on the best way to clean the points. Thanks
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Set the points so that a .020 gauge will pass through... but a .022 will not. That'll get you extremely close to meter specifications.

Clean the points with a small water paint or artists brush, using either Lacquer Thinner or Acetone.
 
Yes there are two grooves 180 degrees out one for each cylinder. The book calls for a special tool and a ohm meter but the timing light works just as good. Those cylinders have very little displacement correct timing is very important for cold starts an fine tuning the carb at idle speed.
 
Got the points all cleaned and reinstalled tested condensers and check coil placement. Fired it up in the barrel and it’s firing good on both cylinders now. Thanks for the help.
 
Good job if you pull the flywheel again just install new points and condensers. I never had much luck cleaning points and getting a full season.
 
I will replace them if I get under the flywheel again. It shouldn’t be used much as it is used for backing up my ‘58 evinrude. I like to troll with a 3 hp once in a while.
 
Use only 16:1. That engine has plane babbitt rod and main bearings. That's the original spec. Good lubrication ensures long life.
 
My bad-24:1. Checked my OMC lube guide. For INFO. 3 hp used 24:1 for years 1952-1963/ 50:1 for 1964-1968. The only 16:1 users
were the 7.5hp models 1951-1958 (the only years made). Sorry.
 
I've read where it is no advisable to clean the faces on points with abrasive paper. Particles of the abrasive can get between the point faces and prevent contact. It is recommended that you use ONLY a points file (small flat file). I suppose that if you rinse off the points with solvent after refacing them you are probably OK.
 
Anybody know why the manufacture of these motors would specify the oil mix to be 50:1 and put that info on the motor? You would think the people that built the engines would know what mixture is required? Maybe they were just intentionally trying to get as many motors to burn up as they could so they could sell more of them?
 
What ?----They never mentioned 50:1 in 1956 for these motors !!-------And in the 1950's they were proud of their product and motors were sold by word of mouth.----Not by liars in slick advertising.
 
racerone said:
What ?----They never mentioned 50:1 in 1956 for these motors !!-------And in the 1950's they were proud of their product and motors were sold by word of mouth.----Not by liars in slick advertising.
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They did on my 1966 3hp Johnson. It says it on the choke cover in bold letters 50:1. I guess they weren't proud of their product in the 60s then.
 
All the early year motors used 24:1 mix because the rod and main bearings were plane babbitt bearings. When they switched to needle roller bearings they went to the 50:1 mix. Since this was a change from a standard that was years and years old I guess they wanted
to eliminate any confusion. For example the 3hp from 1952-1963 used 24:1. The 1964-1968 used 50:1. Big change.
 
oil mixture discussions never end---I do not believe the 3hp models used any needle / roller bearings !
 
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Rambo58 said:
Any recommendations on the best way to clean the points. Thanks
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I strongly don't recommend dressing/cleaning your points with abrasive paper or emery cloth. Abrasive particles can lodge between the point faces and prevent contact. If you are going to try to clean-up the point faces use only a "point file". A point file is simply a very small/thin metal file. If you got one cylinder to spark you could try swapping the coils and condensers and see if the other cylinder fires. I just tore down a 1960 3 H.P. Johnson and replaced the coils and condensers. The points were fine. Even though both cylinders fired when I got it the insulation around the coil windings was cracked like a hard boiled egg.

Be careful when you reinstall the coils making sure they line up with the machined edge on the armature plate.

Bill
 
Rambo58 said:
I’ve been told 16:1 and 24:1 by several people. I mix in the middle at 20:1 figure it’s a safe area in between the two.
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Johnson recommends 16:1 but that was with 1960s quality oil. Some guys run 24:1. I'm staying with 16:1 based upon my previous experience with two cycle motorcycles. Two cycle engines will produce the most power when fed as much fuel and oil as they can digest. This is a plain bearing engine and 16:1 is very safe especially with modern two cycle oil. Heck, when I was a kid there was no two cycle oil. We just used 30wt. engine oil.

Bill
 
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