‘32-34 Radiator cap seal?

[Chris KC]

Interesting pictures Mick, thanks for sharing. Note that on all three there is a clearly defined annular seat for a seal, which is what leads me to think Bob's example may be a replica, from a time when we weren't able to expect quite the same quality as we do now. Or it might just be the light...

[Bob Olive]

Thanks everyone, especially Mick for those three photos. It is clear that my cap is the one on the left in photo 3, but yes you are all correct that it has been drilled through the crest, I imagine in the past to take a small flag post or similar, and yes again, time fettling this might be better spent elsewhere!

[Steve kay]

Oops, a voice from Powys tells me that I was thinking of the wrong sort of wings, so not flared Angel wings, which might not be original at all, but improvised from jumble discoveries. Apologies.

[Chris KC]

Does anyone happen to know what thread was used on the centre post of the caps on the right in Mick's photo?

edit: Ah, found it: 3/16" BSF

[Reckless Rat]

On my RP I seal the rad cap with some silicone. It helps to keep the coolant in the system or at least direct any excess via the overflow. I very rarely have to top up.

[Peter Clayton]

I always assumed that the  cap was designed to  give an automatic screen wash on braking.!!