Can you look at photos of my cam lobes and tell me if they are ok? Thanks

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DennisMo

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Can you look at photos of my cam lobes and tell me if they are ok? Thanks
Can you look at photos of my cam lobes and tell me if they are ok? Thanks
Can you look at photos of my cam lobes and tell me if they are ok? Thanks
Can you look at photos of my cam lobes and tell me if they are ok? Thanks
Can you look at photos of my cam lobes and tell me if they are ok? Thanks
Can you look at photos of my cam lobes and tell me if they are ok? Thanks
 
Those look worn. Especially the timing side intake lobe. The rest show scuffing and wear. What do the followers look like?
 
They are showing signs of wear but not too much, I have no problems still using that cam, maybe use better oil or a mixture of STP with your oil, but if you are going to tear into your bottom end then I would get it reground but only if you doing the bottom end as well.
 
If the cam was removed from the engine (I see it is not), then it would be prudent to measure the lobe heights.
Yesterday I measured the cam lobes on a TR6 engine and though the lobe surfaces look decent, there was a significant amount of wear, such that the lobe lift differed by about .025 from one lobe to another.

With the cam in the engine, if you have access to a dial indicator, a depth micrometer, or a vernier caliper, it is possible to measure lobe lift wear. Keep in mind you can't just compare overall height of the lobe: you need to measure the difference between base circle (the bottom side of the lobe) and the nose of the lobe.

Both exhaust lobes and intake lobes could be worn, so the comparison could be meaningless.
But if you note a significant difference between one exhaust (or intake lobe) to the other, you need a new cam.
Regardless of the condition of the lobe itself.
 
If the cam is showing wear then what would your conrod bearings be like, with the barrels off I be going further with a bottom end rebuild, a cam regrind or new cam and followers reground, a fully rebuilt motor be better than doing a 1/2 job in the long run, but if selling the bike then so many do 1/2 a job and leave the problems for the next owner.
So hard to know with old oil still on the cam to really see what they are like. but if you keeping the Norton a full tear down be the go as you are nearly there.

Ashley
 
I could make that work, but only if I had experience with that cam and I liked it. If your wallet is fat and apparently everyone's is but mine, get you a new cam. You can also surface the tappets if you have a good lapping stone or very flat piece of glass. Example... The tappets shown below had a minor wear divot around the center from using a SS cam, which has a violent ramp that is actually worth it if the engine is built right. Anywho, it takes some time to do the work, but a lot less time than waiting on a machinist to send them back from machinist jail. For the nay sayers... I'm using the tappets shown with the same SS cam I redressed again in my 750 engine. It all works great. All you need is 800 and 1000 grit sand paper for metal and a touch of confidence and experience. Child's play

FlatLifters_6897.jpg


Pre-Commando 750 tappets.
 
I'm quite surprised by the range of replies - all the way from 'it's fine', to 'it's knackered'.
I've already said 'it's fine' on the basis that looking at the witness mark from where followers run there's no discernible step between the worn/unworn part of the cam.
Yes, it shows some signs of wear, but nothing which would impact performance or longevity IMHO, and entirely consistent with all the other 750 cams I've seen.
The late 850 cams I've changed have clearly worn through whatever surface treatment was (or wasn't) applied and they're unquestionably knackered.

I'm curious to know what pass/fail criteria others are applying.
 
This is the lobe that would concern me the most, but as I said, I’d want it thoroughly wiping and a better photo before deciding either way.
IMG_4118.jpeg
 
If that exhaust lobe shown in post #13 is starting to square off, yeah I'd replace the cam. Otherwise it is usable as mentioned by baz, myself, B+, and others. Anywho, I'm not surprised by the replies being all over the map. As mentioned by B+ the wiggly dark areas on the lobes don't mean a thing other than Norton manufacturing wasn't that precise all the way around the lobe. The new Norton cams Andover Norton is selling are probably much better. MAP Cycle sells Norton camshafts for under $400US.

Gotta remember it's just an old motorcycle push rod engine that is not as sophisticated a design as an F1 car engine designed in 2025. A 750/850 Norton engine would run with that cam as is if money was really tight. Would it be ideal? Maybe not. Can't tell

Post an image of the bottom of the tappets as requested earlier on. If the tappet running on top of that exhaust valve is a mess, it'll just get worse if thrown back together as is.
 
Andy Higham said:
Is there an available source of proper induction hardened steel cams? instead of the chilled cast iron versions?
Click to expand...
Yes. Newman cams offer both types.

Andover offer their own super-duper cams, I’ve got their PW3 on the shelf and it does look rather splendid… tho I’ve not fitted or used it yet… seems a shame to get it dirty!

I’ve got a new hardened steel Newman Cams 4S if you want one ?
 
Tappets, lifters, followers (pick a term) look like normal wear and alright although I think they could be smoother and shinier. Might be the camera angle and the fact that digital cameras or phones are high resolution. I buffed mine up some after I took that pic up above before putting them in the engine. However, it may not make that much difference in the end.

Cylinders look good too, but that's the bottom of the bores. Most of the scuffing is up higher if there is any.

Doing that safety wire for the screws is always fun.
 

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