Tillotson Carb Brass Plugs

[Buccaneer]

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.

Prepare to be boarded!

[DAN UMBARGER]

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]

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 2 years ago by DAN UMBARGER.

[frankr]

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]

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]

OK, how about 1/2-20?

[Buccaneer]

frankr wrote:

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]

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]

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 2 years ago by green-thumbs.

[gschnelzer]

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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