These are the brass union assemblies that screw into the front bevel gear chamber of the SOHC cambox and feed oil to the valve guides, via the small bore copper pipes. Similarly, they were also fitted to many pre-1938 OHV rockerbox's.
This assembly is for an inlet valve assembly - as the union has a smaller oil feed hole than the exhaust assembly. Supplied as complete assembly, where pipe can be modelled to fit your engine. Price is per assembly - i.e. one assembly being for one valve guide.
Original Norton unions and copper pipe ferrules were used as the pattern for these assemblies, and we CNC each part exactly as per the original design - including the oil feed bore hole - where the inlet side has a much smaller hole than the exhaust guide version (see Item 0354).
The small brass ferrule then has a length of small bore copper pipe soldered into it to a length that is suitable for all models. once the unions are fitted to your cambox (or rockerbox) you can then carefully bend the pipe to give the best routing to the inlet valve guide - you will find that all original SOHC cylinder heads (and those OHV models fitted with this type of valve guide oiling) will have a small hole adjacent the valve guide that the pipe will feed into. If necessary the copper pipe can be shortened - but sometimes it can be fiddly to get the copper pipe to avoid fouling the hairpin valve springs - hence why we make these pipes fractionally longer than normally needed.
If you do cut the pipe - I find it easiest to do it with a slitting disc in an angle grinder or Dremell, but always de-burr the end, and feed a piece of wire up the pipe aftewards to ensure it is clear. Also, when bending the copper pipe to shape, ensure you support the pipe as close to the ferrule as possible, without actually putting any pressure on the ferrule itself - as it has a fine wall, and can crack if not careful.
The assembly consists of:
1 x Brass oil union (this one is sided for an Inlet valve guide)
1 x Brass ferrule/copper pipe
1 x Brass union nut
1 x Red Fibre Washer (whcih goes on ferrule before screwing into cambox.)
Therefore two sets are required per engine - one being this Item 0353 set, and the other being the 0354 set.
As well as being fitted to all SOHC models, the same assemblies were fitted to earlier pre-38 OHV assemblies - and as per the accompanyning diagram, taken from the 1934 Spare Parts list - if you have an OHV model and not sure if it was fitted with these, turn the rockerbox over and look for small union holes underneath the rockerbox. The second diagram is from the 1948 Spare Parts List and shows how the pipes were typically bent when fitting to the SOHC cambox (although in reality - I have seen pipes with more contorted bends than this!).
As to the effectiveness of this design? - Well Norton's continued to apply it for the full life of the SOHC models, but it is not unusual to find that the small bore pipes clog up with oil and cylinder head 'coke', particularly the exhaust valve pipe - but despite that, I always fit them as designed.