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  1. #1

    Default 1979 Johnson 70 hp compression

    What would be good compression numbers on a 1979 Johnson 70 hp.

  2. #2

    Default Re: 1979 Johnson 70 hp compression

    I have not checked the compression yet, it is a motor I am considering buying, I will be checking compression cold at WOT. My 4cyl Mercs all have about 120 lbs compression. I understand the 10% high low, but what is a good number for the Johnson ?

  3. #3
    Join Date
    Sep 2010
    Location
    ontario
    Posts
    12,221

    Default Re: 1979 Johnson 70 hp compression

    The last 2 Johnson 3 cylinder motors I checked showed 150 PSI on a new gauge.

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