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Thread: 1968 johnson 3hp

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    Member GrassLakeRon's Avatar
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    Default 1968 johnson 3hp

    Your thoughts on a 1968 johnson 3hp outboard. Thanks.

    Ron
    "Equipped with his five senses, man explores the universe around him and calls the adventure science"

    Edwin Hubble

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    small motor, single cil. 2 cycle , it has a sheer pin in prop , if it has been in storage pur oil in the plug hole let set over night before starting
    to lube the rings up some it will not hurt ,an could need a water pump [ impeller] parts ?????? could be hard to get ,,, out side of that what do you wanr to know ? it should work , it will push a canoe , what else can be said SID

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    Is it 3 or 3.5 hp?......single or twin?

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    Quote Originally Posted by GrassLakeRon View Post
    Your thoughts on a 1968 johnson 3hp outboard. Thanks.

    Ron
    If you can get it into running condition, it will be rock solid dependable bullet proof. I have a 1969 4 hp (replaced the one you have in the line up) and it's still chugging along. I"v owned it since I was a teenager, and it was ancient back then. I even ran it submerged once until it sucked water into the pistons and stalled. It's still going. Simple design and newly manufactured parts are cheap and plentiful. Most of the parts are the same from your engine all the way to 40 hp. If you are half way mechanically inclined at all, you can do most of the maintenance yourself. (replacing the recoil starter sucks!) Buy yourself a Clymer's Manual for it; it's a reprint of the original factory manual. Get it for a good price and you can't go wrong. I can't possibly say enough good things about those outboards.

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    Dad had a 3 horse of about that vintage, perhaps a few yrs earlier. Now the younger bro has it and still runs. I remember once Dad said the piston froze up. Dad was not too mechanically inclined, but was cheap. So he took the plug out, or head off, and beat on the piston with a block of wood till he knocked the piston loose. Oiled it up, put it back together and it kept right on going. We used to love teasing him about us breaking out the oars on the way out to our fishing spot so that we would still have time to fish. That teasing went on for fourty plus years.
    Your sarcasm is way, waaaayyyyyyyy more sarcastic than mine!

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    Yeah, Cod, that's a trick my Dad, an outboard mechanic my whole life, taught me ona newer 9.9. (70's). If you have a piston stuck/froze on an outboard, you pull the head completely off, exposing the pistons. Spray auto trans fluid into the cylinder and give it time to creep in. Heat the circumference of the piston on the engine case with a propane torch while you tap lightly but rapidly on the piston head using a cut-off broom handle as your punch and any old baby sledge hammer. The case is aluminum and will expand faster than the pistons due to the applied heat, and, before long, the piston will start to move down into the cylinder. Keep switching pistons and cylinders until it is all freed up.

    Spray some more trans fluid in there and turn the engine over to work the fluid into the rings and hope they reseal. Reinstall the head with a new gasket, new plugs and give it a go.

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    Quote Originally Posted by GrassLakeRon View Post
    Your thoughts on a 1968 johnson 3hp outboard. Thanks.

    Ron
    Hey, check out a website called AOMC (Antique Outboard Motor Club).

    Also check out these facebook pages

    https://www.facebook.com/groups/11131593819/ (Johnson & Evinrude Outboard Motors)

    https://www.facebook.com/groups/49655829434/ (Antique Outboard Motor Club)

    You should be able to get good advice from those guys as well.

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    Wow. Had it out today and it is the cat's butt. Now I have read it should be mixed 24:1 and 50:1. Which one?

    Ron
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    Quote Originally Posted by VernAK View Post
    Is it 3 or 3.5 hp?......single or twin?
    3hp twin plug.

    Ron
    "Equipped with his five senses, man explores the universe around him and calls the adventure science"

    Edwin Hubble

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    50:1 on those OMC 2 strokes. All the way up to the big engines and up to the start of oil injection (1980's)

    I told you it would be good. You can't beat those old Johnson/Evinrude.

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    I believe your motor is still a bushing motor (meaning it has no needle bearing on the crankshaft). If it were my motor, and I do have a couple of older model 3's, it would be run at 24 to 1 or even 16 to 1. And yes they are sweet little motors.

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    Quote Originally Posted by bbstacker1 View Post
    I believe your motor is still a bushing motor (meaning it has no needle bearing on the crankshaft). If it were my motor, and I do have a couple of older model 3's, it would be run at 24 to 1 or even 16 to 1. And yes they are sweet little motors.

    In any case, the only thing you're going to risk by running a richer oil mixture is more frequently fouled plugs. Whoop de do. If you feel better running 24:1 it can't hurt

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    So after running it a bit, the motor wants to die at anything over 3/4 throttle. Does it need carb work? Also I read the only difference between it and the 4 hp is the carb jets. Can I make mine a 4 hp with a carb rebuild kit from a 4?

    Ron
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    Edwin Hubble

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    Quote Originally Posted by GrassLakeRon View Post
    So after running it a bit, the motor wants to die at anything over 3/4 throttle. Does it need carb work? Also I read the only difference between it and the 4 hp is the carb jets. Can I make mine a 4 hp with a carb rebuild kit from a 4?

    Ron
    The high speed orifice needs cleaning and/or adjustment. Get yourself a crb rebuild kit from Sierra (or where ever you're getting your parts) replace all of the little o rings/packing and such. The needle and the needle seat are a matched pair; don't change one without changing the other. (It will cause fuel to leak by and create a flooding issue.)

    I thought the 4 and 6 were the same except for the carb, but that may have been 6 and 8. MOST parts on your engine (all of the ignition, magneto spark plug wires etc etc) are the same from your engine all the way to 40 hp, so there is a good chance that will work, but I don't know for certain.

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    Ron,

    When you get over 3/4 throttle does it just die right off or kinda slow down then pick back up, repeating this cycle. If it dies down then comes back up, your in tank filter may be plugged or your tank vent my be plugged. If it dies down and stays that way at full throttle, I would be more inclined to think of a carb blockage. Another thought is overheating, do you know the history of the engine as to when it last had a new impeller, if not, I would probably change it just to be on the safe side. Also make sure your ignition is in good order. Not sure on the 3 to 4 hp thing, I would go over to the AOMCI.org site and post that question on the Ask a Member section.

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    Quote Originally Posted by bbstacker1 View Post
    Ron,

    When you get over 3/4 throttle does it just die right off or kinda slow down then pick back up, repeating this cycle. If it dies down then comes back up, your in tank filter may be plugged or your tank vent my be plugged. If it dies down and stays that way at full throttle, I would be more inclined to think of a carb blockage. Another thought is overheating, do you know the history of the engine as to when it last had a new impeller, if not, I would probably change it just to be on the safe side. Also make sure your ignition is in good order. Not sure on the 3 to 4 hp thing, I would go over to the AOMCI.org site and post that question on the Ask a Member section.
    I am getting a good spray from the water outlets. I have a new tank. The engine dies at 3/4 Throttle. No shutters, putts, just dies. It doesn't matter how long it is running. In the tank it ran fine, under load at 3/4 its dies. I guess this summer will be a rebuild.

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    I am guessing from your comment that you "have a new tank" that means you have an external tank, I was just assuming you had an internal tank due to the engine you have. OK, so assuming the tank and hose itself are good we can go back to the carb or ignition. Did you try it more than once to go full throttle, if so did it cut out at the exact same spot each time? If it did I would check over the plug wires and ignition real good to make sure you are not grounding out on something at a certain spot. When you said it just dies, that kinda sounds like you are losing fire. Lucky for you, if it does require work, it is a very easy motor to work on.

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    So...reading stacker's comments I have to ask...did this thing set like forever and a day and then you just started it up and ran it without doing much to it?

    If so, you probably should (need) to just go through and replace most of the parts, just to make sure you have a reliable engine. My 4hp sat in a shed for... at least 13-15 years or so...I did;t even mess with it until I replaced darn everything. Parts are too cheap to be up some river some place and have a 20 yr old condenser puke on me.

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    I would definately concur with what FL2AK said, if it has been setting for any amount of time I would go thru it, checking the fire, carb, cooling, etc.

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    And make sure you buy NEW parts, not NEW OLD STOCK (NOS). NOS parts are old stock, meaning they were made forever ago. There is no difference between the coil that's been sitting on your engine for 20 years and the coil that was made 20 years ago and has sat on a shelf that whole time. (Especially impellers and fuel pumps, which have rubber parts in them that dry out over long periods of non-use.

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