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Thread: Johnson "70mod"

  1. #161
    Team Member hupiveneilija's Avatar
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    Some carbs.
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  2. #162
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    the carbs you have 2nd from left are NOT 70hp carbs.
    the black tops came on 60 and 70 from 1992 onwards, and all oval port triples.
    they are definitely not 70hp as wrong size venturi and throat. the smallest of the 70hp black top carbs for a 70hp is throat 1.5 inch with 1.25 venturi.

    no 70hp 56 cu in motors came with carbs with throats smaller than 1.5 inch and 1.25 venturi until 1999/200....
    during 1999 anything was put on all sorts of models just to finish them off.

    the 60hp black tops are the ones with smaller venturi, but not those you have there. what did they come on ? they are NOT from a 56 cu in..

    here is the difference between 60hp and 70hp black tops for the 56 cu in motors.

    the 70hp has 1.5 inch throat minimum..
    .
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  3. #163
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    Quote Originally Posted by filthy phill View Post
    the carbs you have 2nd from left are NOT 70hp carbs.
    the black tops came on 60 and 70 from 1992 onwards, and all oval port triples.
    they are definitely not 70hp as wrong size venturi and throat. the smallest of the 70hp black top carbs for a 70hp is throat 1.5 inch with 1.25 venturi.

    no 70hp 56 cu in motors came with carbs with throats smaller than 1.5 inch and 1.25 venturi until 1999/200....
    during 1999 anything was put on all sorts of models just to finish them off.

    the 60hp black tops are the ones with smaller venturi, but not those you have there. what did they come on ? they are NOT from a 56 cu in..

    here is the difference between 60hp and 70hp black tops for the 56 cu in motors.

    the 70hp has 1.5 inch throat minimum..
    .
    Put carb on the right to intakemanifold to see if it is as big as round hole on intake is.

  4. #164
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    1.50 throat at the back of carb is the size to fit intake manifold.
    the smaller throats are just 60hp carbs.

  5. #165
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    one more thing.
    the number on the carbs stamped 339172 is NOT the carb model number, it is just a casting number that lots of different carbs have, it dont mean anything.
    what you need to find is the real number for these and that was on a very small tag on the carb bowls,
    if you do not have the tag it is impossible to find what carbs they are.
    BUT they look like mine with same jet sizes, but I have different size venturi and throat ??????

    why omc did not stamp correct numbers on carbs is a mystery ha ah .

  6. #166
    Team Member hupiveneilija's Avatar
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    Hey Phill, but that caliper on your biggest carb throat and take picture to see. To intake side.

  7. #167
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    I have pics already. will find them and posy them. Like you my motor was originally 60hp. So I got the bigger 70hp carbs. That is only difference on motors.
    BUT if you ran small carbs then it is impossible to reach 6700rpm. Don't care who says it can or what gauge shows. It will only get to 6500 even with just test prop of 13 pitch. You will not reach 50 knots with small carbs unless you drop the boat from aeroplane.

  8. #168
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    on all the black top carbs the throat is same size at front of carb at air box 1.5 inches....
    on 60hp black top carb throat at the back is 1.25 inches = 31.6mm.
    on 70hp black top carbs throat at the back is 1.50 inches = 38mm.



    your carbs with number 434159 are for 1991 65hp commercial ..


    are you saying that you get 7,000 rpm plus using small carbs ?

  9. #169
    Team Member hupiveneilija's Avatar
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    Quote Originally Posted by filthy phill View Post






    are you saying that you get 7,000 rpm plus using small carbs ?
    Yes, with 1.21/1.37. Aint that funny!

    👌
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  10. #170
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    Want to see that caliper on the throat!

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