1939 Inter Dynamo questions

Firstly, are there no wires to the F and D terminal on the dynamo?  To test it in situ short these two terminals together and test between the the frame of the dynamo and the shorted terminals.  A voltage. Should appear on tick over them raise the revs to see a fluctuation upwards do not rev too high.  Alternatively, with the dynamo removed from the machine connect to a battery, shorted terminals and frame, the dynamo should run like a motor.
If you decide to use this dynamo you will have to polarise and confirm it's output voltage to build into your system.

The regulator, often an MCR2 would be situated on the offside rear stay though some are on the near side as it convenient for connecting to battery.  They have two mounting types, flanged ends or clamp plate, yours would need the clamp plate if you can find one. 

Alan O will be along shortly, he has all the knowledge and material to rewire this machine, alternatively there are on line suppliers of looms.

The Inter might well have had a racing mag and not a magdyno.
Mine (1932) has a modern regulator mounted on the cross connector plate between the two upper rear chain stays below the saddle, because it has no lugs on the frame.
The usual position for prewar rigid Nortons was on brackets brazed to the frame on top of and half way down the right hand upper rear chain stay tube, above the toolbox.
You can of course repolarise a dynamo to whichever polarity you wish.  But Al gets rightly very cross if you end up with the wrong colours for live and earth!  Prewar colours weren't the same as post war.

Jon is half right, Connect D to F yes, but use a headlamp bulb (12V) to earth. If the bulb is bright at a fast tickover then you have 45W?
Polarity? Item on my web site covers this but if you change the polarity then you really should change the earth wire colour to comply, wrong colours-earth wire will lead to confusion and maybe expensive smoke!
The dynamo does NOT have two outputs.-the D is the output and the F is the input that controls the output via the regulator.

Norton (and also Triumph) used the clamp-on type MCR1 that Lucas standardised as their upgrade kit. Most manufacturers used the version with two feet. Fitment was above the toolbox which has the advantage of keeping road dirt off the base but means that the toolbox has to be removed first if the regulator needs attention.

The clamp type are less common but the other type can be converted. The clamp has two hooks and the slotted plate for these is present on all types. The feet have to be ground off, two 'V's cut and a small retaining plate for the clamp fabricated and tacked onto one edge.

I can supply more photos, but the 1939 advert gives the general idea. 

I can supply rewire kits for dynamo and alternator British bikes, the kits include post 1963 colours (tracer) some of the original early colours are not available these days and retaining the original colour system can generate confusion. (dip/main cables both black!)
Original looms? If for any reason you move a switch or it is non original the 'original' loom can become a nightmare to fit/connect.
Don't forget the Vreg electronic regulator.

...of the machine, (which looks to be very smart).  If you intend using it and you don't have a regulator with it then go for the VReg, it's cheap simple and robust, fit and forget.  

If you want to preserve some form of originality you can fit the VReg inside an MCR casing and still have a reliable system.  If you are hunting for an original or already have one get it set up properly. They can work well but they do go off due to the frequency of contact closure.  

looks like the PO was progressing with wiring but did not complete. Cable size especially for the "D" terminal looks a little light so rewiring with a good loom is a good way forward.  I thought brake lights were mandatory post 37?

Are you plunger (option from 37) or rigid?
Cheers
Jon

I forgot a basic, first of all you need to polarise the dynamo. We all know how to do that!!!
Battery must be connected to Earth as intended to use. then take a 'live' wire to the F terminal of the dynamo for a few seconds, at removal this wire should spark, this says you have done the job right and you have a Field coil connected to the F terminal. This polarises the Dynamo and needs to done before you try the output test first, As in the details of the fitting sheet for the V reg.
It is always a good idea to ascertain the Dynamo has an output BEFORE you try using the Vreg.