1920s Norton cams

Norton literature states that Norton used cams marked "90" in the early part of the 1920s. During the 1926 season a different type of cam was standardized on all models and these were marked "W7" (above).

As with many things, there seems to have been exceptions. A pair of "90" cams has been found in a 1929 side valve engine and the inlet had the usual oil pump drive slot which appeared to be entirely correct in form and dimensions; inlet cam driven oil pumps were introduced in 1928, and although one engine is flimsy evidence, the factory may have fitted "90" cams for much longer than stated in the literature.

Racing OHV Nortons used a different cam profile that resulted in much longer valve openings and overlap. The racing cams for the Model 18s up to and inclusive the 1929 models were stamped "IT" although some have different stampings on them - "TTG" or "1.25" (above). The "TTG" form seems to be identical to the "1.25" and has a slightly longer opening than the "IT".

The "TTG" and "1.25" cams in the pictures above are the exhaust ones. The "TTG" cam came from a 1925 TT engine and we do not know whether the inlet cam which went with it (missing by the time Simon acquired the engine) was also stamped "TTG". The fitting of racing cams, as a non standard feature, usually seems to have been mentioned in the relevant section of the despatch records.

Valve timing for the standard cams is:
inlet opens: 25-30 degrees BTDC
exhaust closes: 25-30 degrees ATDC

Valve timing for the racing cams is:
Inlet opens: 42 degrees BTDC
Exhaust closes: 38 degrees ATDC

John's c1925 Model18 Norton

Not a very clear picture, showing a mr John Jempson on his c1925 Model 18.

Viktor's projects

Another email from Viktor: "I´m working on two Norton projects that I have found in the Czech Republic - the earlier one is a side valve Norton with a plain bearing conrod (engine no 6581), the other a flat tank Model 18. Unfortunately, both projects have incomplete frames as they have been crudely modifed to take saddle tanks or rear suspension. I've now invested into patterns of the headstock and I can offer machined castings for around 240 euro. The castings are beautifully made and are cored castings in SG (spheroidal graphite) iron, which whilst not exactly as per Norton (who used so called black heart malleable iron) will be easily strong enough for the job. In more detail, the castings were made from 42CrMo4, based on chemical analysis on parts of the original frame"

Barbara and Laurie's 1923 Model 16H Norton

These magnificent photographs were sent to me by Judith Taylor and they depict her parents on their 1923 16H Norton. Judith: "Regarding the motorcycles, I don't think that there is much of a story really. My parents (Barbara and Laurie) would have been engaged at the time. My father was always a keen enthusiast for 'wheels', but probably could not afford a car just then. My mother always said that she did much of her courting on a motorbike"

Registration OK9675 was issued in Birmingham between January 1922 and July 1923 which confirms my guess that the Norton is a 1923 model. The 16H looks quite new in the picture below. The thing protruding from the top of the handlebars is almost certainly a personal mascot; a doll, gnome, pixie or even a policeman as it seems to be wearing some sort of helmet!

Barbara and Laurie's 1925 Model 18 Norton

This is Barbara on Laurie's 1925 Model 18 Norton. The OM2693 registration was issued between November 1924 and September 1925 by the Birmingham County Borough Council. The motorcycle looks brand new though the passenger footrests and saddle are very similar to those fitted to their 16H.

The photographs were sent by Barbara's daughter Judith Taylor. The photo below depicts Judith in 1954 with her Vespa in Geneva; read the whole story by following this link.

Joe Craig on the CS1 - Moore variety

By Simon

Various authors of Norton books and articles in recent years have remarked on the lack of success of the works CS1s in '28 and '29 compared to 1927. Vague references have been made to cylinder head problems and one chap even went so far as to suggest Walter Moore deliberately engineered the difficulties so that he could justify his departure to NSU in 1929 (a highly fanciful notion to which I do not subscribe!). It should be stressed that these problems are not associated with production versions of the Moore CS1, which were generally accepted as being fit for the purpose for which they were sold. So where did these stories start? Seemingly with none other than Joe Craig!

At the invitation of journalist, former TT winner and publisher of the TT Special Geoff Davison, Joe contributed an article to Davison's 1948 anthology 'The TT Races - behind the scenes.' In it - after several pages of introductory woffle - we come to the nub of the matter. As Joe put it, '...the main troubles of the engines of 1928 and 1929 emanated from a marked tendency of the cylinder head and piston to attain a temperature out of all proportion with the power output...' In the Isle of Man, if one got as far as Ramsey in one piece, climbing the Mountain at high revs in second gear would as often as not result in piston seizure. It seems that Moore's efforts to solve the problem were centred on the piston, which was given increased clearances but to no avail. In Joe's view it was just getting far too hot and expanding accordingly. The source of the problem was poor scavenging and combustion. What apparently happened, after the 1927 season, was an extensive re-design of the head and it seems that those responsible (no names are given!) had not realised the critical influence on performance of the inlet port shape. Norton's engineers, in an effort to follow the valve spring manufacturers' recommendations for improved reliability by using longer springs, had simply altered the head casting, making that section which supports the springs protrude rather more into the ports than was desirable for a racing engine.

On his return to Nortons in the late summer of 1929, Craig and Carroll had a good look at the problem and having identified it, went back to the original 1927 port shape - and one assumes - valve spring length. The valve springs were given a slightly easier life by a rather gentler cam and the result was there for all to see - second and third places in the 1929 Ulster Grand Prix, run at a higher speed than ever before. The lessons learned were applied to the Carroll engines which followed in 1930 and the rest, as they say, is history.......

I have never seen one of the original 1927 works CS1 heads despite years of asking round and of course, the problem is that present owners of such heads might not realise what they had unless they had amassed enough CS1 heads to notice a difference. I even checked the CS1 engine in the Science Museum in London in the forlorn hope that it might have been one of the original type but no luck there either: it seems to be a standard production unit. So if there is any CS1 owner out there who thinks he (or she) has a different cylinder head to the usual type, let's be hearing from you!

(postscript: There are few photos of the '27 works engines which differed from the production versions in a few respects - quite apart from the cylinder heads. The timing cover was a different shape and was in two pieces rather than a single casting, the lower part covering the oil pump was as on the '26 TT OHV engines. The technical artist Francis Simpson did two drawings of the TT engine which appeared in the TT Notes and News (the Motor Cycle, June 30th 1927), above)

Markus's 1926 Model 18 Norton

An email from Markus in Switzerland: "I bought my Model 18 in 1988 in a quite complete - but truly awful condition; everything was completely worn out! 

Not long after I got the Model 18 I found a Model 21 engine which was in very good condition and this is the engine that is currently fitted. The bike uses a Bosch magdyno and lights, dating from 1932 - the year in which electrical lights got compulsory in Switzerland - but these will be replaced by earlier parts as soon as I can find them, as the head lamp is really too large for such a sporty machine.  The restoration took a while and the machine was on the road again in the year 2004. As we speak, the original Model 18 engine is being rebuilt and once finished will probably replace the Model 21 engine.

According the Works Records, the Model 18 was imported into Switzerland in June 1926, and the Model 21 engine in January 1927 by the official Swiss importer “du Mont Frères”. The vendor of the Model 21 engine suggested that one of the “du Mont Frères”  (the du Mont brothers) had used the engine for racing.

Some time ago I happened to stumble upon another Sturmey Archer gearbox and I'm seriously considering using this 'box and the Model 21 engine to build a flat tank racer. As flat tank frames don’t get offered very often, I'm thinking about building a frame myself. Has anyone ever done this before to give me some hints and tips?"

Sven's 1931 Model CS1 Norton

An email from Sven in Sweden: "I found another old photo of my CS1; my father, mother and sister (sleeping in my mother's arms) are going for picknick in the summer of 1948! Note the left-hand side upswept pipe without a silencer!"

1929 16H Norton and sidecar

This photo shows an enterprising shoemaker who had a sidecar for his motorcycle made in the form of a shoe. The Norton is a 16H fitted with Druid forks; note the non-tapered tubes. The dog is of unknown breed and year.

Martin: "The registration number series 'PK' was issued by the Surrey County Council (south west of London) between May 1928 and May 1929 which indicates a 1929 model."

Bert Denly, c1924 Model 18 Norton

Simon: "This is Bert Denly at Brooklands. The silencer makes me think the picture was taken in '26 or so, even though it still shows the early 'straight' rockers."

Roger: "Bert didn't join O'Donovan at Brooklands until April 1923. The Brooklands can rather than the "python" exhaust puts it later than 1924. The cycle parts look very much like the pictures of the Monza record breaking machine in 1924 so I would date the machine as 1924. It is remarkably clean for a Don Norton so that would rule out 1926 making it more likely the pic was taken in 1925."