Norton Camshaft Profile Survey

David Comeau May 2001-Update  Feb  2009

Following are links to a variety of Norton heavy twin cam profiles. They represent many, many, hours of data taking of a sampling of Norton factory, Axtell, Dunstall, Harmon & Collins, Johnson, Megacycle, Norris, Norvil, Pete Williams(Hemmings) and Web.
The newer profiles have been taken on the new cam measuring test fixture I designed and fabricated. Measurements are to .0001" resolution. The main limitation is my seeing and then setting the degree wheel by hand. This degree of resolution shows the variations within the base circle of some cams and brings into question the capability to accurately set valve lash.
  Pix of cam measurement fixture
All the profile data is raw cam lift data measured directly off the cam with a flat or 3"radiused brass shoe, and no rocker arm ratio or clearances are taken into account.
Unfortunately during my early profiling, I did not pay as much attention to detail in the opening and closing ramp areas. On those, only the lift and overlap are useful. The later ones show more detail. I will be going back over the cams I still have access to, and retake the profile data with the extra detail needed. As of this date many are completed, but some cams I do not have access to, and are not likely to be reaccomplished.
NHT cams are either on twin chain (cam/magneto) core or later commando single cam drive chain version.While they have some dimensional similarities, they are not interchangeable.
Norton
   cam100.gif    D12-790 The original 29hp dominator model 7 cam, very mild. It is installed a little more advanced than shown on the graph. This engine comes standard with radiused lifters.
   cam140.gif    21225 This is from a standard model 88. Significantly hotter than the model 7 cam.
   cam110.gif    22729,   650SS and later 750 Atlas grind  with common X2 marking on the twin chain core, know as SS
   cam110a.gif  061084  This cam grind started as the 650ss cam shown above, by now it's called the 1S for the commando, it is the standard cam grind for all non combat 750 and 850 comandos. Lobe centers are 100º
   cam120.gif   063536 The famous or "infamous" 2S  combat cam. Note*** this is MARKED "SS" on the camshaft, but it is not the  650SS (1S) grind.
   cam120a.gif  2S Combat grind with 3" radius lifters.
Dunstall
   cam210.gif   PD04ZC  mild cam not much hotter that a stock cam. A bit more lift and duration, very little extra overlap. Used in my Dunstall Atlas on an 20M3 core and is the same grind later supplied for commando's on a 20M3S+ core.
   cam220.gif    PD R2 B540 WFC, This cam was out of a grenaded  810 Dunstall kit, probably the claimed 75HP version when ALL the mods have been done, including the ported reangled big valve intake head.. The cam I sampled was prepped for needle roller bearings and pressure oil feed to the cam lobes.  Similar grind to the Norton Combat 2S cam.
   cam230.gif   PD/03 E434 WEC, 20M3 core,profiledwith flat and 3" radius lifter, LC 105º, exh .333", int .346", loan by Tom Patterson
Axtell
   cam350.gif   Axtell 5S data courtesy of David Winship. Like a stock cam only with about 5% more lift. But a fair amount more duration  (40º)
Norvil
    cam440.gif    4S camshaft. Actually, very close to 2S Combat when the extra lash clearance is taken  into account!
    cam470.gif    7S camshaft. Getting warm yet?.
Megacycle including their Norris profiles
Caution-Megacycle uses a 1/4-28 bolt to retain ignition AA unit or ignition rotor. vs 1/4-26bsf on english commando 20M3S+ cams.
    cam510.gif      Norris RX data with thanks to John Magyar, a bit more overlap than PW3
    cam520.gif      Norris D
    cam630.gif      56-0NR
    cam640.gif      56N480
    cam610a.gif    56-000/11-01 EOB with both flat and 3" radiused lifters
    cam620a.gif    56-020 with both flat and 3"radius lifters
Johnson
    cam920.gif   NT360
Web
    cam930.gif    86C/12C a touch hotter than 4S
Pete Williams
    cam940.gif      Hemmings supplied PW3  grind-loan by Mike Pappas
Harmon & Collins
    cam910.gif   7014 drag race?  Viscious lift rate off the ramp!!!-loan by Sherwood Shute
    cam 911.gif  7138 A bit more exhaust lift and similar overlap to the PD04CZ-loan bySherwood Shute
Comparisons
    cam101411.gif  M7, 88, 650SS(1S)
    cam1121.gif      1S cam, Dunstall 04ZC cam
    cam2123.gif      PD03-105º, PD04ZC-102.3º, virtually same profile with different lobe centers.
    cam111244.gif  1S, 2S and 4S cams
    cam247.gif        2S, 4S, 7S
    cam356392.gif  5S, NR, NT360 virtual clones....Who made who?
    cam936247.gif  Web8612, 56-020, 7S
    cam9961.gif      Larry Martin's hot rod cam, megacycle 56000 3" radiused lifters
MISC extra profiles
    cam950.gif   A 1970's grind by englishman Lloyd Dickensen, a bit more overlap than the PD04CZ-loan by Roddy MacLellan
    cam120rw.gif    2S on a domi core. This shows a lot of detail on the exhaust ramp and a second set of ramp profiles super imposed on the original profile. This second set of ramps it the "after" of the grinding process that I did to the cam to make it suitable for my purposes.  Pix of cam measurement and grinding process  Norvil sourced, but they claim Norton Andover are supplying them. It has been verified by two others that a 4S (domi and commando core ) and the 2S (commando core) are also afflicted with this design ramps. Care should be used to insure enough valve lash on these cams.