Combat 2s Cam identification

Mensch

Mensch

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Jul 1, 2020
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Hi all. Another 2s cam thread sorry.

I've pulled apart a combat engine which has been done before as it has the superblends in. I had assumed it had the 2s cam but now I'm a little unsure. It seems to have been ground down where the markings should be.





Just wanting to know another way of checking what I have. I'm suspecting it's just a standard cam.

Cheers
 
It could (should ?) be stamped on the face of the cam lobe , if not measure the lift of the intake cam lobe (max height minus the base ), hope this help !
 
The lighting is not so good on the RH side (Primary) of the photos but all of the cam grinding areas seem to have a fair bit of corrosion pitting.
For peace of mind I agree with Nigel - fit a good cam (whatever grind)
Cheers
 
Mensch said:
Hi all. Another 2s cam thread sorry.

I've pulled apart a combat engine which has been done before as it has the superblends in. I had assumed it had the 2s cam but now I'm a little unsure. It seems to have been ground down where the markings should be.





Just wanting to know another way of checking what I have. I'm suspecting it's just a standard cam.

Cheers
Click to expand...

I made the same assumption that my ‘72 combat had a 2S cam. Seems during the combat recall the combat camshafts were replace with standard cams.
 
Thanks all. The photos do seem to make it seem worse than it is. But the consensus is it's now a paperweight so I'm going with all your experience.

Still new to the world of commando engine rebuilds so am keen on your wisdom. Bought the engine to learn.

What's the thoughts on replacement? Another 2s or other?

Have seen the 2s cam on RGM which looks a good price though
 
Last edited:
Mensch said:
What's the thoughts on replacement? Another 2s or other?
Click to expand...

All depends on your intended use and desired characteristics. There‘s no right or wrong per se.

2S is basically a race cam, doesn’t suit everyone.

Standard cam very well suited to what most would consider to be normal road use.
 
Last edited:
Fast Eddie said:
All depends on your intended use and desired characteristics. There‘s no right or wrong per se.

2S is basically a race cam, doesn’t suit everyone.

Standard cam very well suited to what most would consider to be normal road use.
Click to expand...
Thanks mate. Something to think over and go hunting a new cam for
 
Mensch said:
Thanks mate. Something to think over and go hunting a new cam for
Click to expand...
From my experience if you do use a standard cam profile change the combat head for any other 750 head. A nice choice is RH4 low compression or RH6 high compression which Norton Villiers used on the ’73 750. You can still use your 32mm Amals.
 
Whatever cam or compression ratio and ignition timing or exhaust system you use, you must tune to suit. I never change only one thing and expect it to work well. I always check my carburation last.
 
ILLF8ED said:
From my experience if you do use a standard cam profile change the combat head for any other 750 head. A nice choice is RH4 low compression or RH6 high compression which Norton Villiers used on the ’73 750. You can still use your 32mm Amals.
Click to expand...
I would disagree about changing heads. I basically made a Combat head out of my '71 by shaving it and porting it for 32mm carbs. I retained the stock cam. It performed quite well throughout mid range to redline for a street bike.
The 32mm Mikuni's were a little stronger at WOT than 32mm Amals.
 
Since the '72 Combat Commando cases had a breather on the rear of the drive side case, would the '72 OEM SS(2S) cam for a Combat engine not include the timed breather machining on/in the OEM cam design? Reason is the timed breather off the left side of the cam wouldn't be necessary for '72 750 Combat Commando cases and it would be cheaper to manufacture. The SS cam I got from Bob Raber in the early 90's did not have the timed breather machine work.

How many have torn down a '72 Combat engine out of a 1972 Combat Commando they bought new off the showroom floor in 1972 and actually know if the 1972 OEM 2S cam had the timed breather machine work?

Not trying to upset anyone. I'm merely curious.
 
I believe the original combat cam has the left end that can use the timed breather part with spring. Since you have ’72 750 cases why are you concerned about this? The only unusual thing about original combat camshafts is the lack of lubrication scrolling as the combat used scrolled cam bushes. I’m using plain bushes on my engine, but had scrolling machined onto my combat camshaft.
All the aftermarket 2S cams I’ve seen are supplied with that scrolling.
 
Also if you put a different camshaft in there don’t forget to get the stellite surface of the lifters reground. If not my understanding is the cam will wear rapidly.
 
ILLF8ED said:
Also if you put a different camshaft in there don’t forget to get the stellite surface of the lifters reground. If not my understanding is the cam will wear rapidly.
Click to expand...
The standard Norton followers are 20% chrome steel, not stellite, but yes, used ones must be reground with a change of cam.
 
ILLF8ED said:
I believe the original combat cam has the left end that can use the timed breather part with spring. Since you have ’72 750 cases why are you concerned about this? The only unusual thing about original combat camshafts is the lack of lubrication scrolling as the combat used scrolled cam bushes. I’m using plain bushes on my engine, but had scrolling machined onto my combat camshaft.
All the aftermarket 2S cams I’ve seen are supplied with that scrolling.
Click to expand...
Interestingly, mine did not have scrolled bushes (nor scrolled cam). I'm not the original owner, but doubt the PO would replace the bushes with 15k on the odo
 
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