Neracar - Brown and Barlow Carb

[danf19]

I am wondering if anyone knows the threads and size of the fuel inlet connector for the Brown and Barlow carb on my Neracar project. I have tried a thread gage but nothing I have seems to fit.
As you can see from the pictures there is a fine and coarse thread. I am trying to make up a fuel line.
Conversely, Does anyone know what the size the Neracar fuel lines ends ( carb and tank valve) were ??
As always, thanks
Dan
IMG_2080.jpgIMG_2081.jpg

[MMasa]

Have you checked to see if it's a metric thread? Maybe it's a British standard Witwoth?
Mark

[danf19]

Mark:
thanks for the reply and although I don't have a whitworth thread gage, I believe you are correct.
Although I still have a lot to learn with my machining skills , I think I will try to rethread with something a bit more common.
I am using a Harley Davidson JD/Vl petcock off the bottom of the Neracar tank. Would you or anyone know offhand the thread size and type of the Harley petcock ??
As always,
thanks
Dan

[Tommo]

If you ran a vernier over the outside and gave us an idea of the sizes we might be able to assist you a lot easier.
My guess is that the fine thread is BRITISH CYLINDER Thread and going by my B&B carbs would be 9/16 x 26 TPI thread.
The coarse thread looks like 1/4 BRITISH STANDARD PIPE thread and if it is it will be 19 TPI.
BSP differs from the American NPT thread by 1 TPI.
1/4 BSP is 19 TPI whereas 1/4 NPT is 18 TPI
They both should measure close on 1/2 inch over the tops of the thread.
HD fuel tap thread is 15/32 x 24 TPI.
Those B&B elbows are hard to find so please don't destroy such a lovely original part.
I do have the HD tap nut and bull nose that goes on the end of the fuel line.
We have made a run of these in brass and they sell for $25.oo the pair. (1 nut and 1 nipple)

[bobbyt]

Be aware that most British Standard threads are 55 degrees rather than 60. BSC (British Standard Cycle) were 60 degress though, I think. Most BSC were 26 tpi.

Bob Turek
AMCA #769

[danf19]

Guys:
thanks for all the help. Peter, PM sent,
thanks to all,
Dan