Mcculloch 4hp no start

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  • john8504
    john8504

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    #9563

    Hello all! I have acquired a 1968 mcculloch 4hp air cooled outboard that I am having some trouble with. Upon receiving, I was unaware that it had the incorrect carb installed and now I must make something work. I have gapped my points at .020 and I have great spark. However, after priming the cylinder with a little fuel, I cannot get it to fire off. Any info would be great!!

    Much thanks!


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    retiredoz
    US Member - 1 Year
    Replies: 471
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    #73495

    Got anything in the way of compression ? What’s your throttle setting when you try this ? If you retard the timing too much it won’t fire.
    Usually these are pretty straightforward and reliable, but I would gauge from the general appearance that this thing has been idle a while. The first putt is sometimes the hardest to get, I might try using a more persuasive fuel (as in starting fluid or even carb cleaner).

    john8504
    john8504

    Replies: 139
    Topics: 23
    #73500

    Yes it has been in storage at a elderly mans house for many years and then sold at his passing. I have checked throttle in several positions and still nothing. The retarded timing could be it now that I think of it.

    john8504
    john8504

    Replies: 139
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    #73501

    My big question is what position should I have the timing at? My mini mac 35 was 26 degrees ptdc. Are all mccullochs the same?

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    retiredoz
    US Member - 1 Year
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    #73509

    As long as the points are set at .020, you should be OK. I was just referring to the position of the throttle. These are pretty simple machines, but you do need adequate compression.
    The book calls for Champion J18YC plug, set at .035. May not hurt to try a new plug…

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    joesnuffy

    Replies: 285
    Topics: 20
    #73513

    The lower fuel line on there looks a little long looking at the picture it looks like it goes below the carb bowl which I would think would mean the carb bowl might not be filling up with fuel as it should since it is gravity feed. Hope that helps.

    Joe

    john8504
    john8504

    Replies: 139
    Topics: 23
    #73525

    The carb is not original to the motor so the position of the connections are rather inconvenient(hence the long hose). However, because the tank is higher, the bowl is full.

    I couldn’t find anything on the spark plug. I’ll get that one tonight.

    The compression is good at 90.

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    retiredoz
    US Member - 1 Year
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    #73532

    The carb should be a Walbro LMG, I’m not surprised if somebody tried replacing it (not my favorite). Try setting the needles – HS 1 1/4 turn open, LS 1/2-3/4 turns open.. If the replacement is something else, your mileage may vary, of course..

    john8504
    john8504

    Replies: 139
    Topics: 23
    #73538

    Yeah they put a mercarb on it that was way wrong. I have a tecumseh on it now

    john8504
    john8504

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    Topics: 23
    #73539

    Do y’all recommend a specific carb for this engine that would work well?

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    retiredoz
    US Member - 1 Year
    Replies: 471
    Topics: 46
    #73550

    The older style Tecumseh with two adjustment needles is pretty close. The pre-’60 3.6 Scotts used a Tillotsen, and I never could figure why they stopped. MD12A for a while, MD35A, there may be others that might work.
    If you have an old yard equipment repair shop within reach, they may still have Walbro LMGs, I’m pretty sure they had widespread application..

    john8504
    john8504

    Replies: 139
    Topics: 23
    #73756

    So I ended up finding a carb for a 70 3.5 mcculloch on eBay and I’m just waiting for it to arrive and see what happens with that. I hope it works.

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    retiredoz
    US Member - 1 Year
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    #73780

    Some Ebayers know not what they have. McCulloch officially spit the bit in ’69, and to my knowledge never produced a 3.5. But whatever it is may be close enough..

    john8504
    john8504

    Replies: 139
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    #73820

    I looked at it and they might have the year wrong but it looks identical to the once that should be on mine. It’ll be here Friday, so we shall see

    john8504
    john8504

    Replies: 139
    Topics: 23
    #73906

    This is the one I purchased.


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