This item is for a pair of the earliest OHV 'conical' shaped valve spring cups, of the type that were fitted to the first (flat tank) OHV models from approximately 1924-1928. This type are similar in profile to the type that followed (in approximately 1928/29) - but have a smaller spring diameter than the later type, and the innner profile of the top cup has steeper sides than the slightly larger type that followed in 1928 (which is our Item 1029).
Less well known, it appears this early/small type of cups (and of course the corresponding smaller size of valve springs used with this type of cup - our Item 1135 or 1224) - were also fitted to the Walter Moore CS1 SOHC Norton models in the first year of production - 1927, before being replaced by the larger cup type (our Item 1029). They must have quickly realised that the original valve springs and cups were not powerful enough for the additional power and revs the CS1 engines. I am told by old friends with more expertise in the early engines than myself - that most of the early SOHC engines were normally upgraded with the larger conical cups (Item 1029) - but I have talked to at least one customer who still has the original 1927 type small cups fitted - so please check the accompanyning photos before ordering your valve cups and springs - to ensure they are correct for your engine.
Likewise if you own an OHV engine of mid/late 1920's era, as even an earlier engine may have been retrospectively fitted wtih later (larger) valve springs - so please check the dimensions in the accompanyning photos to be sure.
Bottom Cup Fitting: Note that the bottom cups on the type we show manufactured here are to fit over the slightly 'tapered collar' type valve guides - which were commonly fitted to most OHV and CS1 models from the late 1920s onwards (our Item 0676) - as it seems these may have been retrospectively fitted to many engines. But we are also aware that some original (i.e. 1920s) valve guides were of a different dimension collar (and seems likely these valve guides had a 9/16" OD into the cylinder head, rather than the later 0625" OD of the later valve guides. Sorry - but as of June 2024 we only make the one type of bottom cup - so please email me on paul.norman@racingvincent.co.uk if you need to check that these bottom cups will fit your valve guide collars.
For this early type of conical valve cups - we can also offer two valve spring variations:
- Our Item 1135: Short length spring type (see that listing for more detail): This type are copied from a very early set of Terry's original 'New Old Stock' springs, with the description ' Norton Small' type written on them - very rare, but original. However after introducing them - we found that there was at least one longer type (see below) - and that the longer type were more commonly fitted. So please check your original springs before ordering
- Our Item 1224: Long length spring type (see listing for more detail): We have confirmed that the length of these springs were of the type originally offered for Norton models employing the small valve type - and from the enquires we have had so far (i.e. in the last 3 years) most owners of early Flat Tank models using the early valve cups (listed here), also have springs very similar if not identical to the length of these springs
- Both the spring types above are dual springs and fit the valve cups listed here.
Note: Sold as a matching top and bottom cup pair - 2 sets required per engine.
Final point: These valve cups will fit the standard OHV (Mod18/ES2 tapered) valve collets (our Item 0675), if using the standard type OHV valve, that uses tapered collets. If for whatever reason you are fitting SOHC valves with parrallel collet grooves - then contact us for more detail.
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 - this type, THEN A LATER LARGER TYPE: ITEM 1029. Please read both listings and check photos before ordering.
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 1928! - we CNC machine them from solid billet (which has multiple operations due to the complex profile - including radial drilling of the holes), before chemically blackening them. Sorry not cheap - but very expensive to setup and machine in the small quantities we manufacture them.
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