Correct (and as per original) 1/4" BSP 'One Way Valve' - as fitted to all Norton singles, including all SOHC, OHV and SV models - this item screwing into the recess just above the drive side main bearings, allowing the engine to breathe correctly

This special 'one way' valve' looks almost identical to the 1/4" BSP 'straight through' breather that was also fitted to various Norton single cylinder engines, but serves a very different purpose - it being fitted just above the driveside main bearings, and allowing the engine to 'breathe out' but not ''breathe in', which is achieved by the use of small bearing fitted inside the valve.  

This valve was fitted to all SOHC (and DOHC) crankcases (as well as all OHV and Side Valve models) behind the drive side mainshaft casting. On original engines this special valve is almost always badly chewed engines and is now almost impossible to find. They were also fitted originally in bare brass, as shown. This version, like most items I am reproducing, has been manufactured to be indistinguishable to the original, and as normal in this case an original was used as the pattern.

The outer breather union is machined to the same Whitworth spanner hex as the original, is plain brass and has the same thru-hole size as original. It is threaded internally to take a small screw in insert, which retains a small ball bearing (in stainless steel, to prevent corrosion), which provides the one-way breather mechanism.

These should be fitted with the inner screw in section showing uppermost (just in case you are not sure), to ensure the breather allows pressure to escape out - not the other way round.  I get asked by lots of single cylinder Norton customers why their engine may be leaking more oil than normal or not oiling properly - I always direct them first to check if this one way valve has been replaced by a 'straight thru' breather by mistake, or even worse - it is fitted, but is screwed in the wrong way round!

As a final point - like the original Norton Items, our breathers can be stripped for cleaning if ever needed - but it is important to note which way the inner portion is screwed in, as although they look almost identical both ends - they are actually 'sided' with one slightly different to the other.  Once re-assembled, you should always blow through them, to ensure they will only passage of air in one direction

Update July 2023:  Now back in stock - of this popular (and for most Norton singles - very important) part.  FYI - these valves have a lot of setup time and multiple ops - to provide correct dimensions on all parts, including milling.  However - despite the cost of 'Imperial' hex brass bar having almost tripled since we last manufactured a batch 2.5 years - our price increase over that time has stayed far less.  

Good quality Copper washer suitable for 1/4" BSP fittings on most Norton SOHC/OHV/SV engines - i.e. One Way Valves, Breather Unions and Crankcase Oil unions. They can also be fitted to 1/4 BSP petrol taps if required.

Sold as a pack of 3

Update 2022: These copper washers are far better quality than most others I have seen available - they are a good 'close' fit onto a 1/4" BSP thread (most are not), they are not too wide on their outer diameter - just right for Norton unions, and most importantly are a genuine 1.4mm thick - which is perfect for our unions and thicker than most other similar copper washers available.

These may be slightly more expensive than some others you will see - but are the best available I can find (and I have been to a lot of suppliers over the years!)

Note: for many application of breathers and unions on Norton engines - it is usual to find both copper and red fibre washers fitted (sometimes even both togeher!).  I think it is personal preference and have used both types myself - but tend to favour these copper washers over red fibre on breathers and one way valves.  However, if you want a washer that will 'Screw' onto the thread of a Norton 1/4" union or sump plug . . . but is then a good fit on the shoulder behind the thread (which some Norton unions have) - we also sell a special Red Fibre Washer, which we specially thread for this purpose - see item 0249

These are the unions that screw into the crankcase behind the timing chamber - it is the smaller 1/4" BSP side that screws into the crankcase, the larger side is 3/8" BSP and takes the distinctive large oil pipes fitted to Norton Internationals.

These are CNC machined in-house by ourselves from good quality imperial Hex brass, to the original Norton dimensions.

As with the smaller breather union, we also offer a cheaper modern alternative using modern AF spanner sizes on the hex, but the hex on those are larger - while the version you see listed here are copied from a pre-war orignal and are made with the correct Whitworth Hex spanner size and indistinguishable from the original.

I have to say that I have seen SOHC crankcases with original unions both in plain brass (like these) and cadmium plated, but I know the pattern we used for this type came from an original SOHC engine and was in plain brass, and did not have chamfers on either end of the hex (unlike modern equivelants which has a much larger AF hex, does have chamfers, and has a more modern looking cadmium plate finish) - so these brass versions shown here I think look much more correct.   Sorry they are not cheap compared to modern AF equivelant - but they are CNC machined by us - not a mass produced modern version.

Fitted to all SOHC Engines (and I believe also fitted to DOHC engines as well), with two fitted per engine (price is each).  We also sell the correct high quality wide red fibre washers to fit these and ensure they do not mark the crankcases (Item - 0112)

This is the Union that fits into International and SOHC Manx crankcases for both Feed and Return. It allows for the standard 3/8" BSP SOHC Norton oil pipes to be connected. It is very close to original but is a modern item, and uses a larger spanner hex, requiring a UNF spanner. This is a cheaper alternative to the original brass union that I have made specially (Item no 0246), but as you only need to screw it in once this is not really an issue - item is still high quality and is cadmium plated. - Price is per each

This is a faithful reproduction of the straight through union fitted to SOHC (and DOHC) cambox's for connecting the cambox oil feed pipe (fitted at top of crankcase and cambox), but also used as a front crankcase breather on many Inters and magnesium racing engines.  Finally it is also fitted as a breather union on the bevel chamber of magnesium racing crankcases behind the inner timing cover (while Inter crankcases instead employ a pressure telltale unit). 

It has been copied from an original item fitted to an unrestored an original pre-war racing (magnesium) cambox - the union looking like it had never been removed, so I am confident it as was as original fitment from Norton's.

This union has a flat end on the side that screws into the cambox and a taper on the end that the oil pipe fits onto.  It also has a slight chamfer on the side that screws into the cambox, just as the original does (I always fits either a red fibre or copper washer on the end that screws into the cambox/crankcase, to avoid marking the alloy - see item 0249).

Sorry these are not cheap, but unlike modern BSP union's (normally mass produced using AF hex and a modern tinted cadmium finish), these are CNC machined in small batch's from brass and use the correct Whitworth hexagon size

Note:  I have seen these unions in both brass and dull nickel plated (often brass being fitted to pre-war engines).  These are brass finish, which I think looks better, but I may be having some dull nickel plated in the near future. Email Sales@racingvincent.co.uk if you want an update on these

This is modern replacement for the straight thru breather used on Norton crankcases and timing cases. (note: it is a breather - not the one-way pressure release valve also used on Norton engines, this is listed elsewhere). It has a slightly larger AF hex than original, however it is reasonably priced if you are not too concerned on originality, is a good quality item and is cadmium plated

These Red Fibre Washers are a smaller diameter than 'normal' 1/4" BSP washers - but then pre-threaded by us - so they are a good fit on those Norton fittings that used 1/4" BSP thread, but have a groove behind the thread - e.g. Norton pre-48 Oil Sump Plugs and some breather union fittings. 

This listing is for a bag of 5 washers

Background:

For anyone that is familiar with Norton single cylinder models (and earlier twins) - they will know that it was not unusual to make some oil and petrol fittings with a 1/4"BSP thread, but with a groove machined between the thread and the rear face of hex spanner head.  Added this, often the hex was not very wide (what you will see referred to as 'Reduced Hex' by us throughout this catalog for Norton specific fastenings), so there was little hex face for the fibre washers to seal against.  

The two best examples of this are the Pre-48 style 1/4" BSP Norton Sump Plug (in all its guises) and some breather unions (see photographs - some Unions had grooves, while others did not).

Therefore, if you try and fit a 'normal' 1/4" BSP red fibre washer to this type of sump plug or union - it will go on easily, but when it gets to the groove - it will wobble around.  Then, when the sump plug or union it tightened, the wobbling washer will normally move over to one side - and there will be a very good chance it will leak, or just crush and break up when tightened.

In the past we have sold this size of 'tighter fit' washer - telling customers they will need to be prepared to use some force to wind the washer past the thread - but franky - the best quality red fibre washers are very hard, and extremely difficult to wind onto the thread!

Therefore, as part of work we did in early 2022 to replicate most Norton sump plugs, we also looked at how we could make this easier - and eventually have come up with a jig process to pre-thread these washers with a 1/4" BSP thread - as shown here.

So, although not very thick - if you look closely at these washers you will see they have an intenal thread cut into them (see also the taper tap we use for this process) . . . and that means that, although still tight, they can now be carefully screwed onto a 1/4" BSP thread by hand - but will a 'Size' fit on the groove behind the thread - therefore giving a much better chance for the washer to seal properly!

If trying to tap a single washer, it will normally just crush the washer, but with experimentation and a jig, we have come up with a process to manualy thread these washers, so they will just 'screw on' by hand.

This may sound like a simple issue . . . but actually most proprietary 1/4" BSP washers are actually quite loose on a 1/4" BSP thread (see our Item 1111 for 1/4" BSP washers that are a good fit!), but good quality red fibre washers are normally much harder than cheap washers - the washers we use are supplied by one of the best (and most expensive!) washer suppliers - and therefore require this pre-threading process . .. trying to screw it on without doing this is almost impossible.

Sorry these washers are so expensive for what looks such a simple and cheap looking thing - but hopefully you will understand that the jig and time it takes to manually thread them is what results in the extra cost - but definitely worth using if you prefer the original type Red Fibre washerer, rather than modern Dowty (nitrile/steel) washers.

We also sell these as a pair (Item 0941), or close fitting 'normal' 1/4" BSP washers (Item 1111) for those unions and tap fittings which dont have a groove behind the thread 

Distinctive small hex blanking plug/bolt that locates on the left side on the crankcase lower bevel platfom.  CNC maufactured in stainless steel and includes red fibre washer.

This item is an identical copy of the original Norton blanking plug used on Cammy International and M30/Manx variants.  Thread is 1/4 BSC, but it has a deeper 'reduced head' hex than commercially available bolts, as well as the distinctive curved head used on many Norton bolts and a slot for a screwdriver which the original bolt had.  Its purpose is to blank off the vertical oil gallery that returns oil to the feed union if it bypasses the pressure release ball located behind the inner timing case.

We manufacture this ourself from stainless steel round bar, then mill the hex/slot to the correct Norton size, hence why they are not cheap!

Final point - we also include the correct (high quality) red fibre washer - of the same type used on our cheesehead screws.  Although these blanking plugs are relatively small - they are located on a prominent position of the bevel platform, and original (steel/plated) blanking plugs often look corroded or chewed - therefore this high quality stainless item adds a much better finish!

- Modern equivelant Dowty washer (outer washer is zinc plated steel, inner washer is neoprene). This washer is used behind the timing chamber filter bolt and also at the back of the rear cylinder crankcase mouth bolt (that has an oil feed).

It can also be used behind 1/4 BSP fittings - but I prefer to use copper or red fibre on those applications, as they look more original

Breather Pipe (listed in Norton 1948 Spare Parts catalog as Pressure Release Pipe) and 1/4" BSP union nut to fit bevel chamber of all SOHC models (30/40, M30/M40 etc).

These pipes are made from good quality copper and then nickel plated to give an excellent satin finish very similar to the original.  The bend shape and ferrule profile are almost identical to originals (please note - obviously these engines were made for many years, and the profiles did change slightly from year to year - but I took this profile from a pipe I believe to be original).

These pipes were listed as fitting the front bevel chamber (some engines did not fit them though - look for a breather union at the rear of the top bevel chamber face - just behind the magneto chain housing) - however, they can also be used on the front crankcase breather in front of the barrel (left of right) if your engine was fitted with a front breather.  

Note: front breather unions are most common on magnesium SOHC racing crankcases, and can be found on either the left/drive crankcase, or timing side/right crankcase - the 350cc pre-war M40 racing crankcase shown in the photo unusually has two breathers!  Therefore, fitting this U-bend breather pipe is useful for attaching a length of black 3/8" bore breather oil pipe (sold seperately - see Item 0634) to re-direct engine oil vapour down to the bottom of bike onto the road.  

Fitting this breather pipe (and black rubber oil pipe if you wish to do so) adds that finishing touch of originality to your motorcycle - I do it with all my bikes.  And obviously - if you are using your Norton in competition events - you will have to fit these pipes feeding into a 'catch tank' to pass scrutineering.