This item is for a pair of the distinctive 'conical' shaped valve spring cups, of the larger type that were introduced in approximately 1928, and fitted on Walter Moore CS1 engines from approximately 1928 onwards, and OHV models from approximately the same time - through to approximately 1931-32.
It should be noted that this larger 'Conical' type replaced a smaller conical type valve cap, which used smaller diameter springs (our item 1225) - from approximately 1928 - and very early pre-28 SOHC Walter Moore engines may have originally been fitted with the smaller valve cups, but subsequently have had them retrospectively upgraded with this later/larger type of cup - so please check the accompanyning photos and dimensions before ordering. If unsure on either OHV or CS1 models of this era - you can email me on paul.norman@racingvincent.co.uk for more information.
These vavle cups are CNC machined from an original pattern from billet steel before black chemical chromating, including radial holes (for the top valve cup) - and are supplied as a matching top and bottom pair, the bottom cup fitting over the standard type valve guide tapered lip (our Item 0676).
We believe this 'conical' type valve cup were also fitted to the first Arthur Carroll CS1 engines, possibly up to 1931-32, when replaced with the later indented valve cup design (our Item 0672/0673).
All very confusing we know . . . but we have found this out through many years of talking to owners of these bikes, our own or lent to us patterns, and by careful studying of very early Norton parts catalogs or literature. But with all that said - if unsure, please contact us for details before ordering - because we know many early engines have been rebuilt over the years with whatever spares were available at the time!
We offer two types of Valve Springs to fit this design of valve cups - Item 0966 (our most common seller, to fit most 500cc models, or Item 0967 which is a 596cc type).
Note: Cups are sold as a matching top and bottom cup pair - 2 sets required per engine.
This type of valve cup will take the standard OHV collet type (our Item 0675) - providing you are using OHV type valves. Please contact us for more detail if fitting later SOHC parrallel groove type valves/collets
PLEASE NOTE BEFORE ORDERING: There were 2 types of Conical cups (not commonly known) made by Norton - an earlier type fitted from 1924 - @1928 of smaller diameter (our item 1225), THEN THIS TYPE: made from approximately 1928/29, but I am told - sometimes retrospectively fitted to earlier models. Before ordering - please satisfy yourself you have checked both listings and have ordered the correct type for your machine/model - as springs are not interchangeable between the two different sizes
This type of valve cap are now extremely hard to find, this is possibly the first batch made since Norton Motors last made them . . . probably about 1931!
Additional information
You will see that in one of the accompanyning photographs we have assembled the top and bottom conical cups, along with valve spring 0966, our OHV collets (0675). G&S ES2 Valve (0678) and our ES2 Valve guide (0696). Unfortunately I do not have an original valve guide from a 1920's cylinder head, so I cannot confirm that the valve guide (0696) that we sell would have exactly the same chamfer for the bottom valve sring cup as an original 1920s valve guide - but it looks very close. If anyone has an original valve guide, I would be interested to confirm the chamfer - but please email us if you are ordering any of the parts above for your 1920s model and happy to confirm dimensions of our listed part's shown here - sales@racingvincent.co.uk.
We may consider making a batch of the tulip headed valves in the near future if enough interest - but I know of other owners that have fitted ES2 valves (our item number 0678) to their CS1.
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