I have opened a Vac 51 for cleaning out/satisfying my curiosity, what is the correct length (extending out of the feed) and ID/OD for the breather tube? Is it correct for a 1946 barrel date code pen(6.) to have a 1947 marked nib?

I have not opened the vac filler part since I do not have the tool, but I shined a torch from the hood end to see that the sac was OK and it was expanding and folding back well and very smoothly, but I could not see any pellet, only a dimple in the centre of the sac. Were the pellets probably made of darker color or white?

Thanks in advance,
Hari

For vacumatic filler pens in general, I cut the breather tube to a length that will allow it to clear the end of the diaphragm by 1/8" to 1/4" when the diaphragm is fully extended (pump pressed all of the way down).

You won't see the pellet because it's down inside the diaphragm. Color - could be any color under the sun. Black, white, pink, red......

Hi Hari --


Fountain pen dating can be a pretty fuzzy thing. I think it's perfectly possible for a '46 barrel to have sat in stock until it was mated with a '47 nib... and that assembly of a finished pen might not have occurred until some later year.

-- Brian

Missed the part about the date code....

as far as I'm concerned, if it has a gold 51 nib, it has the correct nib. Date code on the nib is a matter of curiosity and little more.