Tillotson Carb Brass Plugs

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  • Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 7495
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    #257487

    Is there a chart or list of brass plug specs so a person could buy
    a brass plug to fit a Tillotson carb, if so desired? I’ve looked on the
    Net, but am not finding what I need.
    The brass “screw slot” plug to access the float needle was stripped out
    on a carb I’m working on. I finally got it out, but decided I wanted a new
    one.

    The plug is a little smaller than a 1/4″ pipe thread, and is 20 tpi instead of 18.

    I ended up making one on the lathe, but it was a tapered plug, and I have
    no taper attachment for the lathe, so I had to tread it by manually turning
    the lathe chuck and moving the cross slide to follow the taper.
    It worked, but not ideal……. pretty sure I just got lucky.
    I decided to go with a hex head instead of the screw driver slot.
    Anyone know of a source for these plugs? Thanks.
    DSCN3285
    DSCN3286
    DSCN3287

    Prepare to be boarded!


    DAN UMBARGER

    US Member - 2 Years
    Replies: 207
    Topics: 28
    #257494

    If it’s a taper thread it must be a pipe thread…correct? If that’s the case just get a brass pipe plug. Our Ace Hardware has them. You can even cut off the hex and cut in a slot if preferred.


    DAN UMBARGER

    US Member - 2 Years
    Replies: 207
    Topics: 28
    #257495

    Now that I look closer the elbow looks to be 1/8 pipe thread and the plug looks bigger but not 1/4 pipe. Don’t think I’ve ever seen anything in between. And obviously I didn’t read your WHOLE post….DUH!!!

    • This reply was modified 1 year, 11 months ago by DAN UMBARGER.

    frankr

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 6715
    Topics: 51
    #257502

    I’m familiar with the plug in question.  They were used on all MD carbs.  However, I don’t know the thread specs.  I suspect it might be something like a 7/16-20 but only run into the tapered portion of the thread-cutting die (??)


    Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 7495
    Topics: 1072
    #257512

    Frank, I believe the small end of the plug was about .470, and the
    round head end, .500. Therefore, it probably doesn’t qualify as
    a 7/16″ (.4375) x 20 thread.
    I gas the round stock a 3 degree taper before I started turning it,
    making it close to the taper on the original plug.
    I got to thinking last night that I should look in the Machinist Handbook,
    to see if there’s a listing of special brass fittings. It’s out in the garage,
    and I’m on my way to the dentist in a bit. 🙁
    Thanks.

    Prepare to be boarded!


    frankr

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 6715
    Topics: 51
    #257516

    OK, how about 1/2-20?


    Buccaneer

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 7495
    Topics: 1072
    #257526

    OK, how about 1/2-20?

    I read last night that tapered threads are measured in the middle
    of the taper to arrive at the nominal size, and of course, pipe sizes
    go by the ID of the pipe.
    Just got home, so will look in the Machinist Handbook, but yeah,
    1/2″ x 20 would be closer perhaps.

    Prepare to be boarded!


    labrador-guy

    US Member - 2 Years
    Replies: 1064
    Topics: 72
    #257532

    Guys they do make a square end pipe plug plugs.  I was having trouble finding a drain plug for my LoanStar boat.  I was talking to one of the maintenance guys at work.  I told him my problem the plug was a loose fit 3/4″ pipe thread.   He went over to his fittings area and grabbed a pipe plug,  here is what you need he said!   “A square tread plug”.  It had an O ring on it for seal up.  It worked beautifully!  I welded a big washer on that plug for easy in and out twist’en.   Maybe there is one of those for your problem.

    dale


    green-thumbs

    US Member - 2 Years
    Replies: 583
    Topics: 43
    #257534

    National Pipe standard has National Pipe Tapered and National Pipe Straight. 1/8″NPT is pretty common and would be my first guess. A good portion of Machinery’s Handbook is devoted to the various thread standards a machinist MIGHT encounter.

    Louis

     

    • This reply was modified 1 year, 11 months ago by green-thumbs.

    gschnelzer

    US Member - 2 Years
    Replies: 10
    Topics: 4
    #257766

    Discount Marine sells the MD carb rebuild kit that includes the brass plug. https://discount-marine-parts.com/tillotson_md.html

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