Cam followers, how much wear is acceptable?

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Colin_McKellar

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Aug 11, 2008
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I have stripped my 850 Mark 3 and the tips of the cam followers are scored but not too badly I think. The bottom of the pads feel very slightly rough and I was wondering what the best course of action would be. Do I replace them? A bit too expensive I think. So do I try and find somewhere in the UK to reface them or do they have to be really bad before any work has to be done on them?
 
Colin_McKellar said:
So do I try and find somewhere in the UK to reface them or do they have to be really bad before any work has to be done on them?
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Difficult to say without seeing them, but Norton specialists such as Mick Hemmings, RGM Motors, Norvil etc. will regrind or reface the followers if they consider it to be necessary, for example, RGM will re-grind & polish them for £10 each: http://www.rgmmotors.co.uk/service.asp and Norvil will reface the set for £46 (+VAT): http://www.norvilmotorcycle.co.uk/workserv.htm

What condition are the camshaft lobes in?
 
L.A.B. has a valid concern - check your cam lobes. The MK IIIs were notorious for having soft cams.
 
I actually thought that the lobes looked good. There were no obvious marks on them. My bike is from one of the last batches and was registered about May 1977 so maybe they had sorted out the soft cams by that time. I believe that the mileage on the bike to be around the 80K mark but a lot of the internals are perfect.

I bought the bike in 1981 and used it for a number of years before blowing the engine up by a stupid mistake caused by ignorance. I didn't change the crankshaft oil seal when I took the timing cover off for the first time since it left the factory and also didn't recognise that the clicking sound that I heard was not a loose tappet but the big ends giving way, ho hum!
 
You could also try "Pete Lovell developments" directly. Pete has a lot of Norton expertise and is very nice to deal with. I know he used to do a lot of work on behalf of Norvil (and probably still does), and may be cheaper going to him directly, than through Norvil.

The RGM price looks attractive though.

l
 
The lobes on the cams are fine. I forgot that I had changed the camshaft when i first split the cases years ago after the major blowup.

I live in Glasgow but there doesn't seem to be anywhere locally that would be able to give me an honest opinion as to whether the wear is within limits or work needs done on them.
 
Colin,
I love questions like this, as I am always wondering what exactly it means when it says "inspect and replace if necessary" Some guidelines/ tolerances would help!

I thought I'd post this photo as a reference. Is the wear shown acceptable?
Cam followers, how much wear is acceptable?


You've got me wondering about those unidentified noises now....

Phil
 
Fastback, your cam followers look a lot worse than mine. I will try and photograph mine and that should give an indication of the wear.
 
Colin wrote;

I phoned Peter Lovell but he was going to be the most expensive at £68 plus £7 postage
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Phew, that is a lot when, as I understand it, that he does most of Norvils engineering work, and they charge £46.00 plus VAT.

Last time I had work done, he suggested that if I had gone to him direct and not through Norvil, it would have been a bit cheaper.

Maybe he's busy :?: Sorry it was a dead duck.
 
Reggie said:
Phew, that is a lot when, as I understand it, that he does most of Norvils engineering work, and they charge £46.00 plus VAT.
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Perhaps he didn't appreciate being phoned up on a bank holiday, and added a bit extra to the price!
 
Refacing the followers is not a job that needs to be done by a Norton specialist. Any competent engineering shop should be able to put them on the surface grinder. It is of course important that they are ground at 90° to the vertical faces.

One point to bear in mind depending on when you did your cam job is that the original sand-cast followers had a tendency to lose the stellite pad. Later (perhaps the last 20 years or so ?) Andover followers are lost-wax cast and have a spigotted stellite pad. Personally, I wouldn't put an early set back.
 
I thought that the followers looked OK but after making a big mistake (again) of giving the barrels to a company to be bead blasted but not taking the followers out the barrels came back with the followers jammed in with grit!! I soaked them in oil but ended up having to tap them out with a hammer as they were so badly wedged in. The company was told to cover the followers but that consisted of the blaster putting his hand over the tunnel, allegedly!

It was only after cleaning the followers that I noticed the damage. I have managed to photograph the followers but when you run a finger over them there is almost no difference or roughness. I still think that the followers got blasted rather than wear and tear.

If someone tells me how to load a photo then I will post the one I took today.
 
The pics seem to magnify the problem. Maybe I just need my eyes tested but they don't look that bad in real life!!
 
They don't appear to have a nice smooth surface to me even if the problem is magnified by the photograph.

If they were mine, I'd get them done, or at the very least get an opinion of someone suitably qualified. The stellite tips are of course very hard, and if the surface is abrasive and not smooth, you will probably end up wearing the cam lobes off quite quickly. If the engine is down, is there any point in putting it back together without getting the followers checked out?
 
Perhaps the cam-surface could be carefully hand-lapped on a flat plate with some valve grinding compound or other suitable material?
 
I think that I am just going to bite the bullet and get them done professionally. RGM seem to have the best price at £40 for the four of them. I will get them sent off tomorrow and Roger at RGM says it will take about a week.

There goes a chunk of the money I had put to one side for a Pazon ignition system!!!!

Thanks to everyone for their advice. It has been appreciated.
 
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