Well done for getting a photo up @David Burnett, not easy if you're not used to this kind of thing! Some more would be helpful if possible. From what can be seen so far, it's a later Radius, post-1938, which was when Radius became a Limited company and they started marking components such. The extra tank fitting is very curious- any chance of some more photos? It seems a lot of effort to go to to drain the tank, seeing as there's a readily removable filler cap which gives the same result. Could it have been a fitting for a pressure gauge, subsequently blanked off?
Dave has had issues uploading images and has emailed them to me to add- Moderators I hope this is ok. I've never used an ipad so can't help as to where or how the photos are stored and how to upload them here. Observations welcomed!
As it seals up nicely the taper thread must be well made. Competently installed, too. The safety release valve and recessed/sunken filler tube are dating clues discussed in this thread. The recessed filler was a refinement to prevent to tank being overfilled beyond a certain level, ensuring enough volume of air remained.
A simple (but incomplete) device to preheat with fuel taken out from the fount. The large preheating - cup is the clue. Radler
