Thread: Johnson "70mod"

  1. #241
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    you will never read the temp of the head by having cool water flow over the sender, that is defeating the object of how the engine is cooled.

    get a heat gun and point it at the head when your gauge reads 50c you will see that the head temp is nothing like the water going through it.

    outboard temp is always measured as head temp, not water temp...

    the water is cooling the head so therefore it must be colder than the head for this to do any cooling, this colder water is also
    cooling your sensor instead of letting you see the REAL temp of the head..
    you are getting water temp with your set up.

    I dont know if there are any specs around about the actual water temp in the cylinder head, I have never seen anything about this for an outboard !!!.

    maybe someone else out there knows this spec ?

  2. #242
    Team Member LittleCharger's Avatar
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    Quote Originally Posted by hupiveneilija View Post
    Ihave pressure fitting there. 3mm hole on the bottom.
    Pistons after taking boat to trailer, few minutes of idling. From up 1,2,3. That is lower tr port.
    Were the piston tops clean when you put this one back together? if so you are running on the rich side in all three, nothing wrong with living on the rich side if your doing long wide open runs, it just means you can keep doing them without rebuilding lol

  3. #243
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    100% agree with LittleCharger , it is better to be slightly rich than leaned out and burn up another block.

    I just measured the amount of water in the head at any one time, it holds a max of 250ml (= US 8.45 fluid ounces) including the thermostat housing.
    ( but not the cover, just level with housing).

  4. #244
    Team Member hupiveneilija's Avatar
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    Quote Originally Posted by LittleCharger View Post
    Were the piston tops clean when you put this one back together? if so you are running on the rich side in all three, nothing wrong with living on the rich side if your doing long wide open runs, it just means you can keep doing them without rebuilding lol
    Yes they were clean not polished. Its a lot on the rich side? Could lean little or what? But coming long run on weekend tells much, i dont do nothing now. After that have to see how pistons look.
    Felt really good to run 20minutes full throttle almost hole time😬.

    Think that stock jet is 50 and now 59, big difference, alltough i use 25:1 oil ratio.

    Blue block waiting for putting together. That will tell what tuner cutting did.

  5. #245
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    when you put the 59 jet in the bottom, what di you put in the top ?
    did you get new 59 jet or did you drill out the old ones ?

    I think shorter tuner will give more top end ? be good to know for sure.
    is the blue block porting the same as the last one ?
    why 25 to1 if running fully synthetic ? that is way too much oil.

  6. #246
    Team Member hupiveneilija's Avatar
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    1&3 is 59, 2 59+.
    Blue has more ex duration. Oil /manual: continous powerboating use 25:1.

  7. #247
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    did you make the jets this size ? or buy them ?
    what size in the top jets ?

  8. #248
    Team Member hupiveneilija's Avatar
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    Drilled. Top is 32, fuel jet.

    Anyone else, is 25:1 too much oil?

  9. #249
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    so originally your carb has 32D top and 50D bottom...but now you have 59D in bottom and still 32D in the top... it is working goof for you with your speed.


    I am thinking put 55D in bottom mains of mine and maybe 60D in the top..at moment it is 50D bottom and 55D top.

    Now I just need to find exact drill size for the 59/60 D jet..........

    .

  10. #250
    Team Member hupiveneilija's Avatar
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    59=1.5mm

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