threaded brass circle on my 1927 tank

[pete kneedler]

Dear Friends:  I am restoring a 1927 Austin 7 (the one with the gas tank behind the dash).   I need the threaded brass circle that fits on the top of the gas tank spout.  I did order a new gas cap from David Claiborne but it won't fit on the tank because of distoration and general abuse of the threaded brass ring on the top of the gas tank spout.  

Cant this threaded brass ring be purchased somewhere in the United Kingdom?  The specialists here are stumped by the thread pattern and think it might be of British pipe origin.  Help!  Pete Kneedler

[Rick F]

Not sure if theses are interchageable with  the tank (my 1929  has a bayonet fitting) but might fit https://www.ebay.co.uk/itm/Austin-7-Seve...SwvvJdxXrr

Later RM/RN tanks have a screw filler - might fit?

[Tony Griffiths]

The simple answer is to make a new neck with the around same diameter but with a suitable American thread, braze it into the tank (usual precautions) - and then machine up a cap to fit.

[Ian Williams]

Why not machine it to the same thread as original Tony? Any good turner can measure the tpi and diameter to achieve that.

[Colin Swinbourne]

If you have the threaded cap, a competent machinist will be able to determine the thread size and machine a new threaded section to fit (whilst taking the obvious precautions!)to the tank.

I’ve just had to do this with my Delage- had the cap, but not the thread to screw it on to so had a new piece turned up...and then had to make the rest of the tank for that to fit to!!

[Chris KC]

Must be someone here who knows what the original cap thread was surely?

[Tony Griffiths]

Why not machine it to the same thread as original Tony? Any good turner can measure the tpi and diameter to achieve that.

I agree, and, a good, competent turner could manage that - but perhaps his friends did not realise when (perhaps) testing the thread with a thread gauge, that the thread angle is 55 degrees, not the usual American 60 - and this caused some confusion as the gauge did not fit correctly? However, we are dealing with a large-diameter, shallow thread and getting that spot-on as a one-off is not easy; I wonder if the American machine shop he tried had access to a Zeus book that should give all the necessary tolerances, etc.?
I've no idea if the diameter is a "standard" or something made as a one-off by Austin - here you can see why it might be a little complicated....
A modern replacement for the Zeus book is the Hague App for the iPhone, though I've not tried that yet, it probably doesn't have BSP dimensions - and would hardly be as handy in the workshop. I wonder if this chart of tank fittings might help - or even one of these as a temporary fitting - or scroll down this page for brass-collar screwed fittings.

[Roy Player]

hi 
Yes we can supply a threaded ring to fit your cap tel 01202  625242 and we will sort it out Austin reproduction parts 
              willie

[pete kneedler]

Hi, Willie: How much will a new threaded ring to fit my gas cap cost? Pete

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Hi, Willie: How much will a new threaded ring cost (for my new gas cap)?

[Jeff Taylor]

Hi Pete,

In case you're not familiar with his company, here's a link to Willie McKenzie's website 'Austin Reproduction Parts Ltd' - his email address is at the top of the home page - cheaper than phoning him from the States !

http://austinrepro.com