Do any of you know if Norton changed their exhaust and inlet valves during the production life of the 16h. I'm not referring to anything pre 1930s. The reason I ask is that I am looking to replace the guides and valves. I have new guides but when I look at the valves they refer to date parameters as if to suggest they differ. For example kidderminster motorcycles have a new old stock but it says 1938 to 1954 (NOT WAR DEPT). Feked advertise new ones as 1934 to 45. I assumed on a utilitarian bike such as the 16h, they wouldn't have seen need to change them.
My engine is pre 1947 with the exhaust pinion driving the inlet pinion, if that makes sense. Its exact age is unclear as it was registered in 1948 but buff the log book is stamped 'ex government vehicle'.
Also has anyone replaced the cast iron guides, I have changed cast iron ones on a 1948 BSA. Anything I should consider.
Thanks in advance,
Rodge.
Roger...nobody came back on…
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Differences...
Good spot David, I certainly didn't see this question the first time round.
I assume that Roger's bike is an ex-WD version with 1936 pattern open valve guides ?
The valves were changed for the 1938 enclosed tappet engines and they differ in at least two ways. Unfortunately, they still physically fit.
The collet grooves were moved closer to the tip. I'm not sure if this was linked to the new valve lifter mechanism or if it was to reduce spring pressures.
More importantly, there was a materials change to austenitic steel and it seems to be the case that these are not considered, if unplated, to be suitable for use in un-lubricated cast iron guides which of course the earlier / WD pattern engine has.
Whilst the same valves were used for in. and ex. on both patterns of engines, they both had differing guides listed which no current supplier seems to do. A visual examination of WD stock doesn't indicate any difference. I suspect that as they were pre-sized (no reaming is mentioned) there was perhaps more clearance on the exhaust guides.
The only valves that I would consider using are the plasma-coated type from G&S in Godalming. Russell Motors stock them.
http://www.gsvalves.co.uk/
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Roger...nobody came back on this? I imagine nobody whom knows has picked this up. But remember the valve cover and lubrication was changed in 1938, but the WD already had the 1934 engines in their bikes so they carried on buying the pre 1938 version throughout the War. But the civilian bikes used the 1938 design after the war. Since the lubrication was automated in 1938, presumably and from what the suppliers have told you, they probably are different.