78 9.9 Evinrude head bolt torque.

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    elgin2

    US Member - 2 Years
    Replies: 108
    Topics: 27
    #1126

    Can someone tell me what the torque should be on the head bolts of a `78 9.9 Evinrude? Also ,what kind of compression numbers to expect. Thanx in advance.

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    avery-omc-parts


    Replies: 6
    Topics: 1
    #13465

    Torque should be 216-240 in. lbs.
    Compression 95 or above is my thought. Someone else with compression numbers hopefully will share.

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    RICK EICHRODT

    US Member - 2 Years
    Replies: 204
    Topics: 47
    #13467

    There are no published compression numbers by OMC/BRP. What you are looking for are compression numbers that are less than 10% apart. If you have one cylinder at 120 and the other at 125, you are good, both are within the 10% range. Now if you have one that is 125 and one that is 150, then you have one that is either scored so bad that it has raised compression or one that has weak rings. The actual number is not important as most compression gauges give different readings meaning that is John brings his compression tester and finds the numbers to be 120 and 125, when Joe comes along and tests it, he might get readings of 115 and 120. Mr. OMC Parts is correct that some engines will run fine with compressions from 80 to 95 while others like to have higher compression figures. AN OMC 1950’s era 5.5 might have 80 and 85 psi while a Mercury MK25 might have 135 and 140. Both will run fine and give good service. It is when you get a weird difference between cylinders that you have trouble. Anything below say 75psi could run but would be questionable. Now please understand that this is just MY opinion and others may differ.

    Have a good day!
    Rick

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