Norton Heavy Twin Cam Hardness/Softness

By Dave Comeau, 3  Sept. 2001 update Mar 2007

Much discussion about soft cams finally made me decide to bring my "inventory" of cams to work and check them on the rockwell tester (C). I finally bought a AMES portable hardness tester and now test them myself out in my shop. Les Emery (Norvil MC) publishes his cams are supplied RC-55 minimum, I have seen no other hardness quoted by any source. I suspect anything under 45 is not to good....15-20 is very soft. Some cams were tested on more than one spot, so therefore multiple readings were posted.....

Here are the results to my amazement/horror.
Genuine vintage Norton
stock atlas-47,
commando3new NOS-52,
commando2new NOS-58,
commando1 good used -58,
commando4 good used-60,
1973-1975 850's
commandoL (1973-750) -25,28,
commandoMikes 75 E-S- 25 (1-12-2001)

genuine norton andover recent 2005-6
mid 40'sRC, chilled iron....split in line with the casting part line, where the ignition AA unit seats, was reluctantly waranteed by NA

Norvil 4S commando-60,
Norvil 7S commando-44,45,48,

Norvil2S domi core-55,
Norvil 7S domi core-60

Dunstall PD04ZC-58,

Mikes Megacycle 56000-11-01  EOB
Shows a mark between two lobes, possibly evidence of a hardness test. My test showed 45-58 (1-12-2001)

Mick Hemmings chilled iron PW3-27