1968 3hp Johnson

[film495]

I was going over this to see about putting it in the water and trying to run it around for 15 minutes or so. New lower unit oil, what was in there seemed real thin, but not milky. Looked over the controls, swapped the broken choke lever out for a good one off a parts motor. I pulled the plugs and the spark seems solid, compression good. The throttle seemed stiff to me so I loosened the screw that adjusts the bushing at the bottom of the arm, but it was too stiff and felt mechanical. When I really looked at it, it appears the flywheel turns a bit when the throttle moves into and out of the stop position. So, the timing advance appears to be hitting the flywheel and enough so to turn it. Is that something that will just break in, or is it indicative of forgetting a spacer or some assembly issue.

I have a few of these, if I want to pull the flywheel I just need, what, a basic harmonic flyweel puller for small engines, and some kind of a strap wrench? I have a torque wrench in a box somewhere to put it back on right. What is the correct nut size? I found I think a 17mm fit it, but a Standard I think it was 11/16 fit it more snugly.

I think the guy put an ignition in it, and it does seem to make good spark. I don't think it was run much, maybe the 2 minutes the guy ran it in a tank for me, is about how long it ran like that. He probably tested it and fogged it, and then a 2 minute test run. He ran a few motors for me in a tank, but if I recall correctly, this one seemed sluggish and did not want to really throttle up. It seemed to run OK, and idle fine, just the top end was missing, like it was a 1.5 or 2hp motor. I haven't found anything else wrong, but the flywheel hitting the ignition seems bad. Hopefully not too bad... uhhhh

 

[Crosbyman]

could be just bad capacitors adjust cam and cam follower to specs ..check coils for cracks don't assume the other guy did change them ... clean the points

measure both HV coil ohms.......... from boots to frame should be 4-8 Kohms

 

[film495]

I'm not 100% sure. It is likely the guy had the 3 hood on the 4 and this is the one that ran strong. I looked at the mechanism on the other ones and one of them does the same thing, but not as obviously, you have to watch it closer. As you close the throttle, you can see the rotation of the ignition plate or whatever it is called, certainly seems to move the flywheel a touch, right as the throttle closes and opens.

 

[tphoyt]

Coil may be to close the the flywheel

 

[racerone]

Coils are not positioned correctly.----Very common mistake.

 

[film495]

I ran this in a bucket, and it started exceptionally easy, idled down really low and seemed to work well enough. It seemed to me to lack the same high speed RPM as my other 68 3hp Evinrude, but I'd have to have them side by side to compare. I might try to run this one a bit on a boat, and start fully going over the 73 4hp I got in the same deal, just cause it seems not to run correct, so - might as well just go over it.

I do like these little motors when they run correctly.

 

[Crosbyman]

I'm not 100% sure. It is likely the guy had the 3 hood on the 4 and this is the one that ran strong. I looked at the mechanism on the other ones and one of them does the same thing, but not as obviously, you have to watch it closer. As you close the throttle, you can see the rotation of the ignition plate or whatever it is called, certainly seems to move the flywheel a touch, right as the throttle closes and opens.

adjust and run fingernail up and dow... should be no snag at all !

 

[film495]

adjust and run fingernail up and dow... should be no snag at al

thanks for the pic and input, now to see if I can actually make sense of it ... lol

 

[film495]

not much to adjust the depth of the coil, just loosened it and pushed it inward with my fingers and tightened it back down. seems like it does not rub now. you could see a bit of wear on the coil, so it was rubbing. I cleaned up the flywheel too a bit, just to clear out any gunk or debree that gathered over the years.

 

[film495]

ran this motor in a bucket again. seemed good. tried to set the high and low a bit, but hard in a plastic storage bin. there's no neutral, too fast and you just shoot all the water out ... but, it works. just let it run for a while, seems to pump water nicely, so - this one is in cue for a water test on a boat.

 

[film495]

ran this a couple days ago on a 14 foot aluminum, seemed to start and run fine, but did not come up to full RPM, it was slugging and seemed to only run at about 1/2 speed. I tried to clean up the carb real quick, but I was in a hurry and goofed it up. I think I maybe poked the threads on the high speed adjustment in the body picking out the old packing, the needle wouldn't thread in correctly and I didn't want to force it. Before I figured out this mistake, I was trying to get the nobs on and think I got one stuck, it seemed like it wasn't popping on far enough, but the needle wasn't threading in, so - when I tapped it a couple times with a rubber mallet, I was just getting it stuck on there good, and now won't come off. I also could not get the main jet inside to unscrew and cracked the end off on one side, so I'm not going to be using a screw driver to get that out.

I was so excited to give this a quick carb clean and I bungled it. I have a 4hp carb sitting there too from a parts motor, if I can get that knob off the needle, I guess I'll have to start over and take my time. I'm not sure what else to do to get that main jet to come out. I could try the body from the 4hp carb, if I did that, what parts do I need to move over - the needles and the main jet? would the 4hp carb work or does that creat running issues.

I'm just kicking myself I didn't get to run this motor again today.

 

[film495]

is there a way to clean up the threads for the needles? is that a hardware store item I can just grab?

 

[film495]

I messed with this for a bit. I wasn't sure what to do with the carbs I had apart, a 3hp that I bungled the threads for one of the needles and cracked the main jet fitting inside trying to get it out, one of the ends the screw driver fits in broke off. So, not sure what to do there, that would be the correct carb. I tried another 4hp carb, but I needed more needle packing to set it up. I had a 4hp carb on another motor that was running OK, so - I pulled it and tried it on the 3hp motor. It started, but I could not get it to run correctly, so - I took the needles off the 3hp carb and tried them, and well - it still didn't run correctly, but I was able to get it to throttle up, and the motor ran in a bucket with more power than I've seen before, but - it seemed like it was cutting in and out, running on 1 cylinder for a while, and then 2. My guess is electrical, it might have run correctly if it was not cutting in and out, but I think I'm dropping a cylinder. I was checking spark and swapped out a plug that I thought might have failed, and the top cylinder seemed to have spark that kept coming and going, so - the plug was likely fine, and I just happend to test it when that side of the ignition was making spark. While I was doing this, I was holding the plug boot once, when I cranked it over, and it fully shocked my hand, so - not sure it is supposed to do that. I should probably go over the ignition on this one again, but I'd also like to get the carb figured out.

 

[film495]

I did some checking with a volt/ohm meter and didn't like the resistance on one coil I had my eye on anyway. swapped that out. still seemed to be cutting in and out on one cylinder, but after messing with it - only when I try to throttle it down, will seem to run full power and the lower the throttle goes, the more it starts to cut in and out, dropping a cylinder. I tried to run on one cylinder and the top worked and bottom did not. I think that was before I put a meter on it, and that coil got swapped out as stated already.

Swapping the coil didn't seem to fix much, but it seems to run at high speed well enough. I have a 4hp carb on it. Before it would idle down to nothing, but I bungled the carb, so - trying this one while I wait on e-bay for a new carb nozzle for the original 3hp carb.

I thought I'd be able to get closer to running correctly with the 4hp carb, but it runs and will drive at high speed so - I may boat test it as is just out of curiousity if anything else goes, or if it does turn out to be an electrical reason why it is dropping a cylinder. The range for tuning the high speed jet is tiny. I'm used to being able to dial it one way and the other, and getting the RPM to fall off a little, and just putting it at the rich side of running strongest. This one, very lean to run, and turn it just the tinyest bit too far, and stall. It may behave different on the water, but it isn't right, so - I should just wait for the 3hp carb parts, waiting on needle packing and that nozzle.

 

[film495]

packed this in the auto to bring on vacation with the tank. It might run OK at higher speed with the 4hp carb, and not sure that is such a great idea to do much, but at the camp I have a 3hp Evinrude of the same year, so - I can also test the tank, and swap the good running carb off it onto the Johnson to try it and see how it goes.

 

[film495]

ran this with the 4hp carb on a 12 foot rowboat, and it was OK, not great - cutting in and out, must be dropping a cylinder. I had another 3hp carb on an Evinrude of the same year so - I tried it, better, still one cylinder cutting in and out. When it runs strong, can tell it should run like a healthy motor. I'll have to go over the ignition again.

I think the carb nozzle I ordered is in my mailbox. I sprayed some more penetration oil on the existing one. Anyone got any tricks to get it out other than heat it up? Seems like this motor and carb should be good, would hate to bugger it up.

 

[film495]

I tried to get that carb nozzle out, with a propane torch, PB blaster, and a set of vice grips that seem to grab good enough, but it doesn't turn, eventually the vice grips turn, and make my nozzle slowly narrower and narrower. I heated it up and sprayed it again and left it. New nozzle on the bench staring at me with contempt and impatience.

One cylinder was cutting in and out, and honestly, I've never seen a twin motor, just have a cylinder go in and out, randomly, at 2-30 second intervals. I figured ignition, and tested the plug wires again, and it really didn't seem like there was a break or short in them at all. I didn't beel like pulling the magneto, but I did find some plug wire - if I had to go back in, it should get new ones at some point, but it needs to prove itself ... lol

I checked the ignition and since I had just checked the coils and replaced one, and the points were already gone over, I put in new condensers. I put the 4hp carb back on it. Seems to run perfectly. No cutting in or out, seems to have power, idles down really really slow. Maybe the 4hp carb will foul plugs or cause some other issue, but if I didn't know the difference, I would not know.

Anyways, running great, ready to put on a boat in a lake and run it.

 

[film495]

Ran this on a 12 foot rowboat today. Granted on a 4hp carb. Seemed to run really strong, idles down super slow. Gave it a few good runs to fine tune the needles. At about 1/3 to 1/2 throttle there is a spot where the motor chirps like a bearing. Found it decelerating, but the same spot is there slowly throwing up. This also appears to be a spot in the throttle where it runs terribly. I assume this is just a shortcoming of the 4hp carb on the 3hp motor. I also got a bit of chirp up at high speed, but I may have been over revving it. I'm 250 and sitting in the middle seat and running the motor with an oar, just almost on plane, which the other 3hp doesn't do. The Evinrude is a weedless drive and this one is the standard gearcase. I think I am going to mix up an oilier gas mix and try it. I think I'm gonna do 24 to one, 32 might run nicer, but I usually run 50 to 1, so the math is easier.

 

[film495]

Still made the same chirp at a mid RPM range on the heavier mix. Ran seemingly the same to me, maybe it just needs to break in a bit. I have no idea the last time it saw any actual use. Sounds like bearing or bushing chirp to me. Maybe it is just a resonant frequency and it is air or a reed whistling. Also a light tap, that almost sounds like valves, noticeable at low idle and follows the speed of the motor. Touch of piston slap is my guess.

 

[film495]

Doesn't chirp at full throttle running 24:1, a little bit at about 1/3 throttle when throttling down. Ran GPS speedometer, 10 mph max on a 12 foot Mirrocraft aluminum rowboat. It will be interesting to compare running when I finally get the 3hp carb put together with the new nozzle. Probably put 3 or 4 hours on this motor over the weekend.