Discussion in 'Norton Commando Motorcycles (Classic)' started by Yorkie, Nov 23, 2018.
These two cams came with a job lot of Commando parts. Can anyone ID each can?
750 on the left, 850 on the right.
69-71 on left, ‘72 onwards on right.
The right hand one could be 750, 750 Combat (ss stamped on the lobes - sometimes) or an 850 cam.
Are the profiles the same?
Combat cams typically were not scrolled
Early 750 on the left, and late 750 on the right, not 850 as the DS scroll is not correct for '70's made 850 cam.
i beg to differ sir.
Same part number (061084 non-timed breather standard) camshaft for late 750 and 850 '72 - '74.
(The '69 - '71 timed breather camshaft also had the same "061084" part number )
Why, as LAB has said, but there are differences, the DS camshaft scroll for the 850 has the scroll break the end on 850 cams, when the 06.1084 was re-introduced the drawing was changed for the scroll to be correct for 850, this was changed in July '74 (amd 10) back to the original scroll end, so one cam fits all. The drawing has no change to the breather portion at all during all 17 amendments.
Many owners note that the when they fit a current cam in the 850 DS case and look in the oil hole, it the drilling enters the chamber at the end of the cam not onto the cam itself, as per the early cams, some leave as is, some nick the metal away at the old timed drive chamfered slots at the cam to aid the oil to enter the scroll.
every combat i have torn down had scrolled cams. i am not saying there were some with the non scrolled cams but i have not seen one.
I checked the profiles and measured the lift on both cams and they seemed the same. Can I fit either to my MKIIa 850?
Out of a Combat I'm rebuilding. No stampings to show it's a 2S but it's higher lift than std. Everything else definitely Combat spec.
@ Yorkie, no reason why not, but I'd pick the RH one as it doesn't have the breather drillings.
MkIIa cams were quite often soft - mine was trashed at 10k. MkIII cams similarly afflicted.
I think these later cams had a lightish grey finish, earlier ones closer to black.
An earlier cam is definitely a Good Thing
SS stamped next to slinger ring IS the combat marking
Good Lord - so it is!
All the others I've seen had it stamped on the side of the lobe or on the end of the cam - never even thought to look there
Are you certain they we combat cams. Many of the combat engines were rebuilt with standard Commando cams which would have scrolled bearing area. The original combat cams shown in the parts book dwg as not scrolled and all the manuals warn not to use unscrolled camshafts with unscrolled bushes. The lobes on a combat when side by side with a standard Commando camshaft are very appearent.
In all my 850 engines, I see the drilled oiler hole the same as 750 with it opening onto the scroll. Only on my MKIII cases does the oiler hole open beyond the end of the shaft....but thanks, I will have to look into this issue farther.
All the cams with marking on the end, that I have seen, were aftermarket cams...like 2S, 4S, 7S or welded reground and end marked. Plenty of other hot rod cams were marked on the shaft area.
All my OEM combat cams were plain shaft.?
Wow. That’s an impressive number of motors.
Not to change the subject, but
HOLY SMOKES Dave that’s crazy. I bet there are even more lurking about too. Kudos to you sir!
The 500-600-650 small barrel are in another part of the shop. Most of these large barrel desaxe engines were bought at an economical price. There are more, but mostly in rolling chassis basket cases, and mostly as research assets/subjects. I try but often fail to keep 3 Nortons road worthy. One each garden gate, featherbed, and a commando. Plus one modern bike(ducati) and a BSA A-10