Cam shaft identification.

Thank you for your replies. They have been most helpful and I now know that I have an early SS cam.

Casting number T2219@3 and stamped X2.

What a great resource this site is. I am much obliged.

Best wishes,

Derek

Below is chapter and verse from last January.

Submitted by philip_hannam on Wed, 30/01/2019

The following info is taken from the unreleased Dominator Service Notes...........

There were four main camshafts produced by the Norton Factory for their standard Dominator engined bikes. All have the casting number of T2219. Those for the Model 7 engine are best avoided if the plan is to rebuild a post 1956 engine and expect a decent road performance from it. The first camshaft was right for the early ‘Iron headed’ engine, in that it helped to produce enough power without the top half over-cooking.

The later ‘Aluminium cylinder heads were able to cope with more power; especially those with the extended finning. So when the 99 engine arrived, with the ‘Daytona’ camshaft in 1956, this had extended times for valve openings, increasing the power, but also the valve train noise. The addition of a 0.010' ramp to its lobes, around 1959, to help quieten down the engine rattles. Hence the title of Q.R. camshaft. These identification letters generally being stamped onto its sidewall.

 The fourth variation of the camshaft arrived with the Downdraft SS cylinder heads. (But was also fitted to the non-downdraft head used on the 99SS).

Basically it was the QR camshaft but slightly altered in profile and renamed as the SS. Most have a casting number of T2219@3. From 1960, this camshaft was a standard fitting for all the Dominator SS engines, including Atlas and Mercury. It even survived, in a modified form, to become a standard Commando part until ousted, for a while, by the arrival of the Combat 2S disaster.

The earliest SS camshafts were stamped with X1 (Bracebridge) or X2 (mostly from Woolwich). The X2 camshafts were supposed to have deeper hardening to cope with the 650 engines power but the late John Hudson claimed that the X1 version was produced with greater accuracy. Later Mercury camshafts often just have the casting number.

The SS camshaft will fit into any of the pre-1960 engines and run quite happily as long as excessive revs are avoided. Otherwise valve float can occur, especially above 6000rpm. But who (track day lads excepted) hammers an engine that much nowadays?

The attachment shows the four Dominator camshafts used in production bikes from 1949 up to 1969. The camshaft on the far right came from a very early Dunstall tuned 99. His later versions having the option of a fitted needle-roller bearing and positive oil feed.

N/T