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.
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.
cam100.gif
D12-790 The domi model 7 cam, very mild. It may have actually been
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 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
comandos.
cam210.gif Dunstall
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.
cam1121.gif
Comparison between stock 1S cam and Dunstall 04ZC cam
cam 911.gif
new
Harmon&Collins 7138 A bit more exhaust lift and similar overlap to
the PD04CZ-loan bySherwood Shute
cam950.gif new
A 1970's grind by englishman Lloyd Dickensen, a bit more overlap than the
PD04CZ-loan by Roddy MacLellan
cam910.gif
Harmon&Collins 7014 drag race? Viscious lift rate off the ramp!!!-loan
by Sherwood Shute
A group of profiles with exagerated intake lift, i.e. nonsymetrical
with exhaust
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.
cam440.gif
Norvil 4S camshaft. Actually, very close to 2S Combat when the extra lash
clearance is taken into account!
cam930.gif
WEB 86C/12C a touch hotter than 4S
cam220.gif
Dunstall 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 to the Norton Combat 2S cam.
cam620a.gif
Megacycle 56-020 with both flat and 3"radius lifters
cam470.gif
Norvil 7S camshaft. Getting warm yet?.
cam111244.gif Comparison
of Std, 2S and 4S cams
cam247.gif
Comparison of the 2S, 4S, 7S
cam936247.gif Comparison
of Web8612, 56-020, 7S
This group are for all practical purposes are clones of each
other and basically symetrical profiles
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)
cam630.gif
Megacycle 56-0NR Norris grind
cam920.gif
JohnsonNT360
Comparison within this group
cam356392.gif
5S, NR, NT360
Lift continuing to grow with more lift and overlap than the
previous group
cam940.gif
Hemmings supplied PW3 grind-loan by Mike Pappas
cam510.gif
Norris RX data with thanks to John Magyar, a bit more overlap than PW3
cam520.gif
Norris D again, a touch more overlap and lift
cam610a.gif
Megacycle 56-000/11-01 EOB with both flat and 3" radiused lifters
Now for the big boys
cam640.gif
Megacycle (norris design) 56N480
MISC extra profiles
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.
cam9961.gif
Larry Martin's hot rod cam VS megacycle 56000 3" radiused lifters
