Hello Trevor, George and John, thanks once more for your input
Trevor - I'm familiar with Balsa cabin having visited them many times over the years - all the timber for the Huntsman build (elsewhere on here) came from them but thanks for the thought. I can truly commiserate with you on the radial - I began a Bentley Br2 in 1992 and like you have a collection of many machined parts sitting idly under the bench. Despite putting in so much work off and on over the years I have, I'm sorry to admit, little inclination to resume work on it.
As an aside Trevor, as you live in Norfolk, are you aware of the Forncett Steam Museum just south of Norwich. They hold a very good 'Model Engineers Day' each October which is well worth a visit - lots of stationary engines, steam boats, traction engines etc . Maybe see you there this year?
George, again thank you for your observations. When I re-assemble it after painting I will take your advice and replace the O ring with a small spring. I was totally unaware that silicone O rings could grow by such an amount. I will bear your comments in mind once final test runs on steam are carried out.
John, I assume from your comment you are referring to the 'make up' of said distributor block. I did not take any pics but basically there were two holes drilled right through from each side at the correct angle (18 degrees). Two further holes were drilled, one from from the top the other from the lower surface to break into each of these holes. (These two holes were opened slightly to take small plugs which were silver soldered in place when soldering the pipework). Two further holes were drilled from the cylinder end to break into these plugged holes. The whole was then set up with the pipes cut to just protrude into the block by about 2mm and held on the jig as shown - once the unions were tightened this was all 'self holding' ready for the soldering. Once soldered all four unions screwed onto their respective points on the engine without any stressing.
Hope that resolves your query John.
Thanks again guys, your comments are much appreciated.
regards - Ramon