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650SS camshaft advice needed

Submitted by john_ward1 on Sat, 08/04/2023
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Heavy Twins

My 650SS project came with a matching numbers crankcase and a complete 'donor' engine. I was told that the engine had been "tuned for racing" and having taken it apart, it's certainly had some modification made to it. I believe that the camshaft that had been fitted wasn't the original profile. Check out the attached photograph. The shape of the cam lobes looks a bit different. I want a machine that is happy on the road, not the race track so I'm expecting to have to find another camshaft. Roger Bacon's book says that there were a number of different cams fitted over the years but isn't very specific about any of them. I've seen a couple advertised that have a "2S" designation. Would that be suitable for a road bike?

I apologise for being a bit long winded but this is my first Norton project and my knowledge base for these machines is quite small. I hope that will improve over time. 

John

Attachments
650ss-2.jpg

Submitted by peter_shand on Sat, 08/04/2023

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That cam looks to have longer duration than the standard cam, lift wise it could be higher as well. The standard cam is/was a good profile. For road use there is nothing to be gained by fitting a 'performance' cam of whatever profile, it usually takes a few horsepower off the bottom end to put a couple of horses up at the top and it will give the valve gear a harder time of it. 

Loads of people have been suckered into fitting higher lift/longer duration cams only to find there bike is hardly any faster and is louder to boot. If you think about how you ride, you spend at least 95% of the time at less than 3/4 throttle, completely negating the top end gain . Fit a standard cam and enjoy the flexibility it will give and the easier, less stress on a 60 plus year old engine.

I know of a 99 fitted with a PW3 that doesn't get ridden faster than 60mph.  

 

 

Submitted by philip_hannam1 on Sat, 08/04/2023

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John.......find a moment or two to check out the latest version of the Dominator Service Notes. Chapter 5 page 22. - Camshafts.  This has some useful information and tips.  A quick link is just to the right of this posting.

For a 650SS engine you will need a  camshaft marked with T2219@3.  or something similar. Those marked with @2 or @3 generally have profiles more suited to pre-1958 Dominator engines.  It might be worth you contacting Newman Cams. (Surrey / Kent border) For many years, they have specialised in manufacturing Norton Twin camshafts and know their business well.

Submitted by robert_tuck on Sat, 08/04/2023

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Comparing that cam to a new 2S  reveals a much longer duration and probably more lift as well. As Peter says ,a bit too much for everday riding . Decent 650 ss cams are often sold SH,  I don't know how a 2S compares to a std 650SS ,  My 2S is still in its Andover Norton packaging if you are interested.

Philip... Thank you for the link to the Service Notes. What a splendid document that is. Most informative. It would seem that I should be looking for an X1 or X2 camshaft. If anybody has a good one that is surplus to their requirements, I would be happy to negotiate for its transfer of ownership.

John

 


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