Hello to all,
My 77 850 is in the process of being rebuilt and the camshaft is showing signs of wear. This was supposedly replaced less than 100 miles ago with the lifters, mains, rings, hone, and crank grind, etc. All appears to have been done and is in good condition except the camshaft. The paper work history supports the sellers claims and the original 16 thousand miles on the odmeter.
I bought the bike and have not ridden it as the brakes and steering head were in urgent need of replacement, so once the Fuel tank was off it was obvious the frame was bent. This has been repaired. At this point I was unsure as to the engine rebuild quality so I removed the engine and gearbox and decided to do a full rebuild myself to be sure there were no demons waiting to show themselves.
I have read lots of posts regarding cams and their care etc, But what cam should I buy to replace the worn cam?

What grind? ( I intend to use the 850 as a tourer, sometimes two up, sometimes the red mist may appear)

Who sells a Quality camshaft?

If it makes any difference, the bike has Paizon ignition, and two standard Amals, although these may be changed to Mikuni later.
Regards Graeme.

Graeme,

I reckon the standard cam is great for touring and is easy on the valve gear.

The latest white iron cams from Norvil are very hard wearing, you've just got to be carefull when fitting the timing rotor as the cam is bloody brittle and can crack. I've used RGM regrinds with success the stelite tip never wears, although after a high milage the follower can, but they are cheap to resuface.

While you've got the motor in bits check the bigend shells are in correctly and the oil drilling in the rod isn't covered.

Cash

Hello Cash,
Good idea with a regrind, I hadn't thought of that option.
I've checked the rest of the bottom and all is as it should be, just the camshaft. (and gearbox bearings and bushes etc, )
This bike sat from 79 till 95 I have been told, so isolastics and swing arm and wheel bearings too, etc, etc.
Regards Graeme.

I used a Web cam when I rebuilt my Combat. Unfortunately, after some 13,000 miles, a piston top let go. When I tore down the engine I found excessive cam wear. I called Web and spoke to the owner. She questioned me about the oil brand I used. When I told her Mobil 1 she became very agitated. Lack of zinc, which is hard on cams. Not to be used in our Nortons. Anyway, she offered to rebuild the cam for $100.00 and supplied new springs, retainers and lightweight collars for another $100.00. I've yet to fire that engine up, but I assume she must have some confidence in the quality of her cams. BTW, I used the 12a grind. Not great on top end, but a real stump puller.

Hello Jim C,
You've hit the nail on the head with your comments regarding Synthetic Oils and their lack of Zinc.
The fellow I bought the bike from said he had only used a Shell brand Synthetic oil since the engine was rebuilt.
That explains why the rest of the engine looks like it's just been rebuilt and the cam is badly worn.
That's a trap for people new to Nortons, (like me) thinking they are doing the right thing.
My future camshaft thanks you!
Regards Graeme.

I will hijack another thread, is a PW3 a race cam only or does it make a good fast road cam with some improvment over a standard cam,I realise the standard cam is a good cam and was once the race cam for norton twins, but technology advances on.

Sorry chaps but I can't grasp this need for zink, I've used semi and fully synthetic for ages without a problem. While I used mineral oil I did in two new cams and in both occations it was the cam material at fault not the oil. The white iron cam (hard and brittle right through) Norvil gave me as a replacement was ran with mineral and synthetic oil and hadn't 0.00001" wear on the lobes when it cracked. I replaced it with a RGM sellite tipped regrind 14000 miles ago and I've got it beside me now (took the motor to bits for another reason) there's not a scrap of wear on it or the followers.

I reckon the main problems are poor materials and or very thin case hardening not the oil. Just use what you are happy with and change it often.
Cash

Hello Cash,
After Jim C's comments regarding his experience with a new cam and the manufacturers comments regarding zinc in certain oils, I read a few articles on zinc in oil on the net.
They mostly state that zinc in oils is recomended for pushrod engines which require an oil with a high load capacity, such as big bore and pushrod engines. (older harleys were mentioned)

I agree with your comments about poor case hardening and the quality of the metal used. What's different with Commando cams and other valve spring cams? Other cams still run on rockers or shims, they've still got to act against a spring load. And I've never heard of so much concern regarding how a cam is run in etc, until I started reading posts here about the need to look after cams.

This could turn into one of those oil debates.

I use mineral oil in old bevel Ducati's and synthetic in more modern Ducati's, but that's mostly due to the different big ends in each. Nothing to do with cam wear or other factors.

It's all interesting though.

Regards Graeme.

Splatt,

The PW3 cam would also be suitable for the road, it gives really good midrange, and a little more top end than a 4S. It's been designed to exploit the characteristics of the commando engine. I used one on the track for a long time....i could come out of a hairpin at 2000rpm and lift the front wheel without dipping the clutch!

http://www.redlineoil.com/msds/50.pdfl

If this URL works it shows the Zinc content of Redline motorcycle oil. I guess they think added zinc is a good idea too, but actual hardening of the cam and tappets is probably more necessary to remember if fitting a new valve train. If that was not a problem folks would not have developed the hard and fragile cams.

I guess I can't link to that because it comes up as a PDF. Just go to the Redline site, tech, motorcycle oil MSDS.

Thanks Swoosh.

Redline definitely quotes a high zinc content. That's about 10 times what Rotella T has and it's suppose to have a lot.

Redline is used in a lot of flat tappet racing engines at high spring pressures.

The problem with empirical evidence is one never knows how close you are to failure. Problem is failure is usually not a gradual thing. Failure occurs once protection falls below minimum thresholds. Many bikers swear by their favorite oil. "I use ACME 5-80w and never lost an engine". I believe the Norton cam lubrication is barely adequate. That being said, I opt for a high zinc content oil. I personally now have a case of Torco T-4M 20-50w. Another aspect I think our Norton's need is an oil cooler. I spoke at length with an engineer from Spectro. He claimed when oil temp in the tank reaches the 240°F you are at risk. Keep in mind the oil reaches higher temperature in other parts of the engine, especially the head. With a meat thermometer in the oil tank I found the temp near 240°F. I now run a Lockhart cooler. Temps never get beyond 220°F. According to the Spectro engineer it's also important to have oil temp reach a minimum, hence the need for a bypass thermostat.