Crankcase Identification

The image you've shown seems to be ok to me -  but what is the number like on the left-hand crankcase curved part ?   Cheers, howard

The engine number that you have shown is the Engine Shop number, so your 99, must have been the 49th one built. I saw a 1958 500 Norton Nomad on Ebay, once and it had a 132*** Commando number stamped on it. If you contact the NOC twins records officer, he can look through the factory dispatch records, for your 99 49 Engine Shop number, and find out exactly what your engine number should be, as well as to who and where it was dispatched to.

As you say - it doesn't look good.  The engine number was assigned to a late 1955 600cc Model 99.  The engine number would have had the Code L14  somewhere around the Patents badge.  The actual number will have been approx 15000 units earlier than the number now shown - 79761.  I would be inclined to look for a more complete and useable  set of cases.  Have a look at your frame gearbox etc and decide what you want your Norton to be.  If you decide on one of the first  Model 99's with dynamo, Burman type gearbox and clutch etc then you should find suitable replacements.  It your frame is from a later period with alternator, AMC gearbox and clutch etc then buy to suit that choice.  Have fun and be careful buying from e-bay.  Cheers, howard

Barrel  and cases. look alternator type to me likely  from  59 to 62 ish.  Is it registered  ?  Could be stolen or unmatched case halves. Could work ok but may be a problem getting it registered. What frame do you have.?.

If you just register it with the number it now has, I doubt if there would be any problems. But now you know a bit about it, it has become something to worry about. Pity you cannot register (or try to register) it before spending time restoring it  just to protect from the remote possibility that anyone at DVLA knows or cares about Norton's numbering system. After all...we can retain the registration on a pile of parts that used to be a bike, but not as far as I know vice versa.

Sounds possible that they are matched case halves, Made in late 57 and would have been logged as a 58 model, normal practise for Norton. So you can build  a 99 engined  650ss . Must have been one of the early coil ignition Dommies .What type of head do you have?.

If its important to you to have an engine with its original stampings then you could switch cases with the other 99c set. A fair amount of work ,especially if your assembled motor is in good nick. Having said that I cannot imagine fitting any motor until I stripped it completely and checked all out.  

Looks like a nice straight frame.  Worth a few basic checks with straight edges and string lines before painting.  The early engine will need a dynamo and mag and really should be in a wideline ,so I would build another bike !, The 99c motor could run a dissy or mag and 12v Alternator , And look like an early 99SS if that's your style. I would buy a 650 crank and rods ,mix with what you have ,(modify a case for more room) and build a 650 with a bit more reliability than the 99. All to his own.

Hello john  now the Model 99 started life in September 1955 and shop number would have ran from there on , until september 1957 when the alternator cases where made and a new set of shop numbers came out for the alternator cases  So the ones you have with the 49 shop number on it is the correct shop number but the rest are fake numbers as the stamp sizes are wrong for Bracebridge street, So now you need to write to the heavy twin's officer  with your details                And I would not go down the 650 route using barrels from a 600 and cases  as these items are not designed for a 650  and these cases are early alternator and therefore will not take a 650 crankshaft So now these are my thoughts And I believe I am not far wrong,  yours  anna j 

Hi John.......I can add a litle more information to your numbers game.

22707Y ......... the 'Y' informs that this Norton cylinder head was produced by one of around six different casting sections in the foundry. Each used a letter to help ID their products. Other letters included M, N, K etc.

Whether to go for alternator or dynamo depends on which crankshaft you have.

If you want to explore the Rev range and give it some, you should consider some aftermarket rods or look into the 650 route where new rods are about although not cheap.Alternatively you could gather some more "bits"  for a 99c  so if a big bang occurs you are prepared.

Hello Rob now these early crankcases John has are not ones you can go down the 650 route with only cases you can do this with are the model 99ss and after April of 1961 as these where built with 650 Manxman cases to late 1962 yours Anna j

The Atlas cases could be a basis of a good strong engine, The problem is that little appart from the timing gear,cover,oil pump,  Dissy/mag and cam  nothing from the other motors can fit. It is possible to build a 650 in the 99 cases ,but that needs a little cutting and welding.Might be usefull if you give us a full list of what you have . 

Hello john sorry but Atlas cases will not make 650 as barrel mounting studs are set farther back and are reduced studs So that will not work right I would stick with the 99 motor as it is after all its the frame that's registered not the motor ,that motor as.not been touched in years and the chances are it maybe fine inside and may only need a good clean and a change of bearings as a.matter of course, and then a rebuild and timing before fitting the head the head will need a good clean and a good look over and new bronze guides as old cast one have a habit of giving up the ghost and breaking and doing damage to the head and you then do a small amount of porting as you just may get that extra 5bhp if every thing is set up right now have fun and stay tuned your Anna j 

Enough to be going on with then!.  Seems to me that you can build a servicable 99  that  will be Ok for normal restrained classic use but need some new rods if you intend to ring its neck.  Or an Atlas that with the right gearing and some balance work will provide a beefy classic for chuntering about. Neither are really up to high speed long distance stuff  compared to modern machinery. An Imp featherbed four seems a prospect too. Surprise us!, Build all three.

The alloy rods apparently have a finite life and suffer from fatigue, as we have no way of telling what they have been through its a bit like Russian roulette. My own 99 has done some 40000 miles and at some time had a partial seizure. I also think the big ends are a thou or so oval.I try to restrict the revs but on occasion hit 80 mph . probably playing with fire now. I would rather use new forged Norton Rods so the best route seems to be convert to a 650 crank (with case and barrel skirt mods). The 99 barrel is in perfect nick at +10 and 650 pistons and the 99 head and the rest can stay. If I want to go mad I have other rides availiable to me.

What a toodo, I would, horror of horrors, put a Triumph lump in it! You have all the rest for a cafe racer. I have a similar problem with an Atlas. I also have some Triumph engines as well, and parts are easier to find. Better still, stick a Suzuki GS1000 engine in it, also front forks and wheel. It could then be the new Norton Dommy Garner almost made. Just taking it a bit. If one were to use the Dommy motor, it would be wise to split the crankcases and check it measures correctly to drawing. I have had to do that with a welded up Commando 850 engine on my production line. I found it 10 thou out of shape, not bad for a weld job!

Hope you get it sorted John. Best regards, Paul

The 88 motor with its shorter stroke ran smoother than a 99  so it was revved higher and more often . It did not  unduly suffer broken rods unless the crank got filled with crap or the drive side piston overheated and seized or the lubrication failed for some other reason and then the drive side was often the failure point. The longer stroke 99 put more strain on the rods but "in the day" was not an unreliable motor. Interestingly the rod blank was the same as used in BSA twins .They did not seem to suffer breakages but the usage and other design differences could be a factor.The twin motors I have worked on have ALL suffered a seizure on the drive side at some time, must have strained things a bit. I have heard that steel rods do not suffer from age, but alloy does.So a very long period of "rest"  is a mixed blessing perhaps.There are a number of club members who have had Norton rods wreck an engine with no obvious reason. Not happened to me yet. Fingers crossed.On the lookout for a 650 crank and rods !.

For those of you interested in the development of the Dominator.........John Hudson told me that when the Factory began to put together engines for racing (Daytona Bikes), in the 1950s,  they began to experience failures in several areas once 7000rpm was being exceeded. This included broken conrods, crankpins and pistons. The conrod and crankpin failure problem led the development team to investigate enlarged crankpin diameters of 1.60" and even up to 1.75".  At one point they even purchased and fitted Triumph conrods in an attempt to get better reliability.

Crankshafts with 1.75" crankpins were tested on some of the Nomad 500cc machines and also used on the later TT racing engines along with a reduced diameter bore of the pin centres. The latter modification carried over to the production engines along with a better finish to the pin itself, especially at each corner section where it meets the flanges.

In the 1960s Gus Kuhn organised the manufacture of around 50 short stroke  Norton 500cc twin engines for racing. These basically had 650 crankcases and cylinder heads, seriously shortened 650 barrels (with 7 fins) and a modified 500 crankshaft.. Apparently they were not a great success. Wonder if any are still around???

I used 7000 as the change point with my 88 for many years  ,this was also the point that the standard valve springs began to loose track of the SS cam , possibly why it was never a problem on shortish runs.  I did however seize the motor  at over 90 mph  after a flat out run from Keswick to London. Lubrication failure. I experienced super braking  from high speed for the first time ever!.Even then the rod did not break,but the motor never  regained its ability to keep alongside a proper 99SS in a drag race. Sold it and bought a supercharged  998 frogeye.

I need somebody to explain to me why it is 'i' bfore 'e' in siege but not in seize.

Many years ago Peter Williams mentioned the amazing amount of distortion a crankshaft went through when changing gear at high revs. He also said that people do not realise the damage done to a crankshaft following a bad seizure. This damage not being visibly obvious but enough to cause replacement main bearings to fail very quickly and the crankpins to be no longer aligned. Thus affecting the ignition timing.

... there's a story that after the move of Norton from Bracebridge Street to Woolwich one of the turners could never get parts to the right dimensions. All his mates tried as well as the foreman and none could do it. Eventually they contacted the chap who'd run the lathe at Bracebridge Street. He said "You did remember the plank when you moved the machine didn't you?" "Plank?" "Yes, you wedge it between the lathe headstock and the wall to keep it steady".

Probably apocryphal however maybe a nugget of truth there.

Of course both Japan and Germany had their industry virtually totally destroyed so had to restart with new kit while Britain soldiered on with antiques.

Post photo of Mad Mitch's girl

She must have been exceptional???

Mike