1957 Evinrude 35 HP Big Twin

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  • johnny

    US Member - 1 Year
    Replies: 79
    Topics: 18
    #267094

    My 1957 Big Twin won’t idle. It runs great at all speeds but it dies when I reduce speed approaching a dock or maneuvering into tight spaces. Adjusting the idle needle doesn’t help. I would appreciate any ideas or help to get my idle back.


    reivertom

    US Member - 2 Years
    Replies: 764
    Topics: 39
    #267095

    Check the compression. Low compression with do that. They will run OK at higher RPMs but stall at idle. IIRC, they should have around 100psi, and not lower than 90. They should also be within 10% of each other. Also, some cheap gauges will read low, so try to use a decent one.

    • This reply was modified 2 months ago by reivertom.
    • This reply was modified 2 months ago by reivertom.

    dave-bernard

    US Member - 2 Years
    Replies: 1907
    Topics: 29
    #267104

    Idle circuit in carb needs cleaning.


    billw

    US Member - 2 Years
    Replies: 1909
    Topics: 62
    #267105

    My money is ultimately with Dave’s solution; but it is ALWAYS good to start with a compression and spark test, pretty much every time, so you don’t go off half-cocked, down some worm hole. You don’t want to waste time or money if the compression is bad. Also, with Big Twins and others, it perfectly possible that spark on one cylinder might be dropping out at low speed. Check compression first, spark second and then go after the carb. When checking the spark, make sure in your case, that the mag plate is in the idle position, because sometimes, wires chafe and will only short out in one place in the throttle travel.

    Long live American manufacturing!


    crosbyman

    Canada Member - 2 Years
    Replies: 2929
    Topics: 281
    #267107

    if you haven’t serviced (replaced) the plug wires   measure the coil  ohms  from boot to frame grd  while rotating the mag plate from fast to  idle   look for s  steady reading 4-8 Kohms

    ….sometimes all you need is a crack in a bend somewhere  to  loose sparks

    Joining AOMCI has priviledges 🙂

    • This reply was modified 2 months ago by crosbyman.
    • This reply was modified 2 months ago by crosbyman.
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