Thanks guys! Yes, Im aware about this spacer between instrumental panel and front plate. British carriers used a bit different setup, there are two separate spacers left-right from Langite (which is compressed cork gasket I believe). Actually, you can see my spacers in the upper corner of the picture - they will go on the proper place eventualy. And thanks for heads-up about the dome nut, Lynn - my fingers are grateful to you
There is no bypass valve visible, because my engine uses a bit different setup - there is built-in bypass valve - see my sketch. Seems to be clever to me, hopefully it will work properly