Machined Camshaft Profile

What camshaft is it? 

Hi Martin,

   The valve needs to open and close at a graduated rate so the valve gear is not over-stressed. Cams with extensive profiles (ramps) are used with flat profile followers and the ramps provide the gradual opening and closing action. The cam profile you have are used with radiused followers and it is the profile of these followers that provide the gradual action. If you have bought the camshaft from a reputable source, there shouldn't be a problem. 

Thats interesting. , I have a NOS Hemmings 2S cam with its packaging and instructions. It does not state its designed to use with Radius followers ?. I will get it out and compare with your Picture. Perhaps there were several versions made?.

Is there a definite 'line' between the base circle and the flank of the cam? The ramps of a cam lobe are usually quite short, not very wide at all.  The nomenclature used when describing cams can be much mistaken.  The ramp is the bit between the base circle and the flank, often described as the 'quietening ramp'  Which is a bit funny when hearing these engines run! The flank of the cam is where the majority of the valve lifts occurs. I've never heard of the 2S commando cam requiring radiused followers.   

From the drawing the 2S has its base circle removed to enable it have a clearance circle which is different, it looks like the clearance circle has been ground after the cam has been ground. This would produce a ridge of about 0.009'' in height. 

The photo is not good enough to make a good comparison but my new 2s has an definate change of direction but no step or sharp line at the end of the base circle . While we are talking  2S cams , When i rebuild my 99  who thinks a 2S would make any improvement on the std 60 Daytona ?, normal classic use ,mid range the important area.

Fit  a cam with the now standard commando profile which stemmed from the 650SS profile, it was good enough to win the thruxton 500 miler so why fit a cam that will give the valve gear a harder life and be noisier to boot.

Of interest, the comments on camshafts in the recently serialized Commando service notes says 'Avoid the SS cam like the plague'  

Says it all really

I have a 4S camshaft which was fitted with standard cam-followers in 1988.  No wear is apparent on either component.  I am using a slightly modified system for the valve springs, which makes the machine smoother and should lead to less wear on all parts of the valve-train. I am not aware of the top speed since last year’s rebuild but the bike is nice to ride; as Robert mentioned earlier, mid-range is much more important.  The B676 [Melton Mowbray to Colsterworth] and the B664 [Market Harborough to Uppingham] are good examples in Leicestershire [and Rutland and Lincolnshire] of where the mid-range is very suited to the roads; a village every two or three miles with nice bends or straights between them.  If you still need to go faster, might I suggest that you purchase a BMW S1000RR?

   Peter S., hi. If th service notes refers to avoiding 2S cams, I can understand. Whereas, the "SS" cam (650SS-500SS) is what th commando "Single S" cam is probably developed from. As you say, all good for road use. l have ridden all these, including a 500 SS with a Single-S .(Thread added to the nose) .600Daytona cam is also good, Tourquey,  softer, up to 90MPG cruising. Maybe. my point was, the designation of "2S" & "SS" is often confused. P.S. l would like to hear a comparison of sport riding between 4S and P.W.3.

   . .barry. .

To clear this confusion up, the now standard cam 06.1084 was developed from the Domiracer cam, the grind is the same, and yes the drawings exist. It is a very good cam and maybe why Norton re-introduced it mid 1974. 

I recently bought a new Commando cam with SS stamped on side of left most lobe. It is uniform dark colour all over. Anyone know what it is and whether it is the one to avoid?

@Ashley: What is stamped on the 2S camshafts you sell today?

Both th 2S Combat camshafts that l have seen, visually have th inlet lobe flanks assymetrical near th nose, a bit like an early breaking wave profile, or reminiscent of a "hooked" sprocket tooth. One of these cams had a lot missing from from some lobe-tops; well used. l will be using "Cam-Running-In-Compound" when assembling an engine with new cam & followers. Not a 2S cam. 

Check that th lobes will clear th barrels ,follower tunnels as well as th cases ,as they turn. 

I believe the service notes can create confusion here, because they clearly refer at times to the 2S cam as the SS (likewise the 3S as the SSS). This appears to stem from them being referred to as such in period factory service releases. As previously mentioned, they are different, the SS being a very good allrounder, combining good mid-range torque with top-end power, whilst the 2S, introduced in the Combat engine, lacks mid-range. Hence, if there is a reference to 'Avoid the SS cam like the plague', this is really misleading, as it should no doubt read 'Avoid the 2S cam like the plague'. A bit ott perhaps, but there are better cams out there. It is a pity the notes cannot be amended to correct this.