Pistons Notched and un notched ?


Pistons Notched and un notched ?

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Home Forums Breezeworks Pistons Notched and un notched ?

This topic contains 2 replies, has 2 voices, and was last updated by  Rake 11 months, 2 weeks ago.

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  • #17250


    Hi All,

    I’m just rebuilding my 1978 470 and it needed a poston so I got one shipped from the USA and is has a notch in one side.
    The others dont and the service manual advises that the must either all be notch or all but un notched and not to mix ones that have a notch and ones that dont.

    I now have 3 unnotched and one notched – is there a reason they should not be mixed ?
    Will I be able to proceed or must I now find another piston ?




    Mercruiser used many pistons in the 470 over the years. Some were forged and some were cast. There are also differences in the forged and cast groupings . I would replace the pistons in sets. You don’t know if you have cast or forged pistons. Some even have different diameter wrist pins.

    Go here and pull up Mercruiser Manual #8. Pages 3A-37/38 and look at the many pistons specs. You will need Adobe Flash Player.




    Thank you stractor.

    I was being told by both the seller and some folks on another well known forum that mixing would be ok so long as the new notched one faced front.
    Looks like I will have to buy a set of the federal mogul ones from falcon marine so I have a balanced set all the same.

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