Repairing brass needles

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  • johnyrude200


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    #2330

    Needless to say, I don’t think this was ever intended to be done, but I was wondering if anyone has tried repairing the tapered point on your typical carb needle?

    The reason I ask is because I of course run into ones that have been ruined due to over-tightening. Fortunately I have a good supply of donor carbs from dead motors, but it’s always a shame to toss out the old needle. As an experiment, I took a badly damaged needle and hand sanded the taper very carefully with a fine grit emery cloth. The taper was of course no where near as fine as original, but once I fired the motor off, I was still able to use the screw to adjust the low-speed settings and see it working OK. A much finer level of sensitivity with the adjustment (in other words, smaller window of adjustment between lean and blubbering rich, say, 1/3 turn instead of a 1/2 turn…this is a 1968 20hp…usual adjustment is 1/4-1/2 turn out).

    I couldn’t help but notice that there seems to be a couple of different tapers for many of these carbs; one that seems to feather out over about a 1/2 inch, and a more ‘stubby’ one that is more like a 1/4 inch. I have noticed on the old 9.5’s, that the finer tapered needle provides a lot more leeway for adjusting than the stubby version, for obvious reasons (smaller clearances allowed with the finer tapered needle).

    I have been finding myself holding onto broken items, to perhaps experiment this winter on salvaging things that are damaged. For instance, I have recently run into two gearcase housings where the shift shaft bearing orifice is cracked or marred enough where the bearing no longer stays in (so can’t get a good seal on the o-ring).

    It’s probably a NO-NO to JB Weld that bearing in permanently, as it would be the last time that housing could be used, but I suppose that wouldn’t make a difference if/when that day finally arrived because it only took 45 years for the thing to wear out this time.

    And on a complete tangent: I’m wondering what’s going to happen if we ever move away from fossil fuels to all of our motors?


    frankr

    US Member - 1 Year (includes $3 online payment fee)
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    #22509

    Lots of people have touched up needle points by holding a file against them as they spin in a drill (drill press preferred). Better yet, do it in a lathe.

    The degree of taper affects the sensitivity of it. That is, how quickly it opens or closes in a certain amount of rotation.

    I would Locktite that bushing in place. The blue stuff can be disassembled pretty easy. Red probably would need heat to 350 F to get it out. Do the same with seals that are loose in the case.

    You young guys can do the worrying about fossil fuel. It ain’t gonna happen in my time left. But I am concerned "they" might make me quit burning my fireplace. Yeah, with thousands of acres burning every summer, they are going to say my stick of firewood makes a difference?


    garry-in-michigan

    Lifetime Member
    Replies: 3583
    Topics: 31
    #22523

    Back in the dim past, when I had access to a good lathe, I would sometimes make my own from stock originally bought for shear pins. This was sometimes necessary because renewing the taper shortens the needle valve which can cause the carburetor cover to interfere with the adjusting knob. I found many outboard owners resent the stops placed on the cover because it makes it harder to stop the leaks from dirty float valves by turning in the adjustment valve. . . . 😆


    johnyrude200


    Replies: 782
    Topics: 186
    #22524

    Glad to hear from some experienced mechanics, that what I decided to fool around with was still within the sector of reality!

    Thanks again guys, hope all has been well.

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