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What engine do I have?

Submitted by stuart_stow on Wed, 10/09/2014
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Nortons - General

Hi all,

Im new to norton ownership having just purchased a cafe racer with a norton engine installed. Im trying to discover exactly what the base engine is in the frame. The log book says its a 495cc, the engine number seems to suggest its a 1952 500cc model. But im having trouble decoding it with the details i can find online

I believe the main engine number is 41976 G12

There is another number stamped close to it T5790 for which I can find no reference.

Its fitted to a 1956 featherbed frame.

Can someone please help with identifying what the engine actually is please ?

The gearbox is also incredibly stiff to get into first or come back down through the gears from forth. Im expecting to have to rebuild it, but if anyone has any sugestions then they are most welcome, even if its what to look for once ive stripped it.

Sorry if any of this is a but basic for some of you, but im just starting the learning curve having been into modern bikes for some years. I think im going to have to raid my fathers old tool kit too.

Regards

Stuart

Submitted by ian_cordes on Wed, 10/09/2014

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That number appears to indicate that it is a 1952 497cc Model 7 engine, Stuart. Not exactly a racer, imo! Does it have an iron head and barrel?

Silly question, but you have checked that the gearbox has it's correct quota of oil? I bought a Dominator once and found the gearbox to be stiff. Lack of oil was the problem, and a top-up soon cured it.

Ian

Submitted by stuart_stow on Thu, 11/09/2014

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Previously ian_cordes wrote:

That number appears to indicate that it is a 1952 497cc Model 7 engine, Stuart. Not exactly a racer, imo! Does it have an iron head and barrel?

Silly question, but you have checked that the gearbox has it's correct quota of oil? I bought a Dominator once and found the gearbox to be stiff. Lack of oil was the problem, and a top-up soon cured it.

Ian

Ian

Thanks for that, took a magnet to it as the barrel is painted black, and yep thats iron. So it would seem it is the Model 7.

I havent had time to check the oil level yet, will see if i can get round to it this weekend, lots of other jobs to do on it first.

Regards

Stuart

Submitted by phil_hannam on Fri, 12/09/2014

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G is the factory production year identifier - in this case 1952. But the factory model production year generally ran from September, in one year, to the following September. So G could cover a late 1951 machine.

The 12 indicates that the engine is for a Model 7 bike. This would also have appeared on the frame if your bike was original and kept its single front downtube frame.Later Featherbed frames were stamped with 122 and later engines stamped with 88 or 88SS. Apart from the engine, many of the model 7 parts were borrowed from the ES2 (single engine) bike built around the same time.

The engine number 41976 puts it roughly as manufactured at the beginning of 1952, or even possibly a late December 1951 engine.

T5790 is the Engine Shop Number - T standing for Twin Cylinder. So this number shows the engine as number 5790 of a batch.

See attachment for similar crankcase from a 1953 model 7.

Attachments model-7-case-jpg

Submitted by ian_cordes on Wed, 17/09/2014

Permalink

Previously stuart_stow wrote:

Previously ian_cordes wrote:

That number appears to indicate that it is a 1952 497cc Model 7 engine, Stuart. Not exactly a racer, imo! Does it have an iron head and barrel?

Ian

Thanks for that, took a magnet to it as the barrel is painted black, and yep thats iron. So it would seem it is the Model 7.

Stuart

Sorry Stuart, it wasthe head in particular that I meant to question, as they all had iron barrels. A 1952 model 7 would have been fitted with an iron head originally, which could have subsequently been changed for a later ali one; assuming it would fit; that was all.

Cheers

Ian

 


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