High quality (UK manufactured) coil valve springs to fit 1920's OHV models up to 1933, early (Walter Moore) type CS1 models and the first Arthur Carrol SOHC CS1 engines up to 1932/33 - see detail listing for more information and if your machine requires this type of spring. Price is for a set of 4 springs (i.e. enough for one engine)
These springs were fitted to the 1920's models and are easily identified by the valve cap that were fitted to these OHV/CS1 models of the 1920's - which as can be seen in the accompanyning photographs were deeply recessed and conical in the centre, so that the inner spring fitted in the recess of the central recessed part of the conical top cup.
They have been manufactured by a well established UK spring manufacturer, who makes all our valve springs. An original set of 1920's Norton valve springs were used as patterns, and they are shown in the photographs, next to ours, along with a pair of original top and bottom valve spring cups of the same era - where the top valve spring cup has an easily identifiable conical shape with radial drill holes.
It is hard to be precise about years - but according to most information availble it seems this type of valve spring was fitted to both OHV and CS1 SOHC models up to the end of 1932 or possibly 1933, at which time the spring design and valve cups was changed so that the inner spring was a greater diameter than this early type (although the outer spring seems to be identical).
Looking at different Norton Spare Parts catalogs - this type of spring cup and springs were shown listed in 1928/29 for CS1 and all OHV models (although the Model 19 springs may have been different - see Item 0967) - at which time the Walter Moore 'Cricket Bat' type CS1 engine was current. At this time the part numbers for these springs were 4058/59
However, the same style of valve cups and springs were still shown listed as fitting OHV and CS1 models in the 1931/32 Spare Parts catalog, by which time the Walter Moore CS1 had been superceded by the better known Arthur Carroll SOHC design (that later became the International). It seems this earlier valve spring design carried over first of the later type CS1 engines, before being superceded in approx 1932/33 - but by then the part numbers for the springs were referred to as 3X60/61 (the '3X' being a common way of identifying part numbers in the early 1930's).
I believe the Terry's numbers for these springs were: VS114 (1920's OHV) or VS109 (pre 34 SOHC).
By the time of the 1934 Norton Spare Parts Catalog came out - the valve springs and cups had changed to the later design (the springs being type 3076/7, our Item number 0889). We also sell spring sets of that later design which replaced this early type - Item 0889, but although they are similar, the later type used very different valve spring cups (see Item 0673 which is the later type 1930's valve cap) - if your engine uses that later type of valve cap, rather than the type shown in these photographs, then you will require valve springs 0889 rather than this type. If unsure, please email for detail.
Talking to some knowledgable Norton people about this spring design - I have heard a view that it is good coil valve spring design to have the inner spring touching the outer spring on compression - and the later (Item 0889) design shows an inner spring much closer to the outer spring, which may be why Norton's changed the outer spring only on the Post 1932 design. However, if you have an earlier type engine (i.e. 1920's or early 1930's), but fitted with the later flatter (i.e. not conical) top spring cups - this may because previous owner's had changed over to the later spring design later in the motorcycle's life.
If you are unsure - then email us with your engine details and we will try and help identify the correct spring for your engine.
Note we also offer a very similar spring to these - Item 0967, of which were listed by Terry's as being fitted to the 596cc OHV model (presumably late 1920's), which look to use the same valve cups, but are of a different length again.
IMPORTANT UPDATE MAY 2022: Please note that we are currently checking with some owners of early flat tank and 1928 CS1 owners - it is looking likely that very early Walter Moore CS1 models (i.e. 1928) and pre-1929 OHV machines may have been fitted with smaller diameter valves spring cups and springs - that although looking very similar to these, are actually of a lesser diameter. As soon as we have verified this, I will update this listing . . . but please contact us before purchasing if you intend to fit these (or valve spring cups - Item 1029 that fit with these springs) to a pre 1929 CS1 mode or OHV model - as earlier springs and cups may have slightly different diameters. FYI - the outer diameter of these Item 0966 outer springs are @42.5mm OD. If we verify a smaller/earlier type was used - if someone is able to supply a pattern, we will manufacture a batch. I have an original Norton spare parts supplement showing this type fitted in at least 1929, so maybe they changed the diameter some way in the middle of the Walter Moore CS1 production run, realising they needed to be stronger?