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BA Threads - Printable Version

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BA Threads - Sparky Boy - 29-07-2022

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Hi, does anyone know the Standard Thread of the fixed ignition point on a DJ4 Distributor. Information available suggests BA sizes were in use in the 1930s. Thanks in anticipation.


RE: BA Threads - dickie65 - 29-07-2022

I use a BA Spanner on my points.
I suspect its a 4 BA but I would need to confirn it.
0 BA is a large thread size and the numbers go up as the diameter goes down.


RE: BA Threads - Tony Griffiths - 29-07-2022

A useful chart for tapping drill sizes for BA threads: https://maccmodels.co.uk/ba-size-chart/
A complete specification chart here: https://www.ring-plug-thread-gages.com/PDChart/BA-thread-data.html


RE: BA Threads - Dave Mann - 30-07-2022

The early fixed contact is 4 BA and the late fixed contact is 3 BA.


RE: BA Threads - Sparky Boy - 30-07-2022

Many thanks to everyone for their response. It is much appreciated.


RE: BA Threads - winchman - 30-07-2022

If anyone needs any BA Taps and Dies I have plenty spare, I will swap for 7 bits too