Reliable camshafts

Norton used to make good reliable cams. The cam below is an early 750 cam with proper hardening. These cams worked fine without problems. Later on when the 850s came out - everything went to shit.

The cam above has been cleaned up. You can see a few rough spots but its holding up well.

The cam below (at 25,000 miles) is a current cam but designed for radiused lifters.


The corresponding lifters for the radius cam.


Its all about proper material and hardening. Web cam lobes are hardened to about 58 HRC. Plasma nitrided billet cams are hardened to about 60 HRC.

I'm not postitive but I think the "Stellite" (Delchrome) lifters are 52-56 HRC.


The worst experience I've had (many years ago) was with a well known supplier with a suspect reputation. I (dirt poor racer) was tempted by the low price but I heard rumors of surface problems with his cams so I called him and he personally reassured me that they were good and there would be no surface problems. After a few hours running the hard metal surface came off and metal shavings came loose to circulate in my carefully prepped race motor - embedding themselves in my crank shell bearings. I've never bought any internal parts from his since.

The lobe on the left appears to have more wear on the right side. Is that due to camshaft deflection?

Nitrided is a 'like' minimum quoted figure usually given as 60HRC , it is usually found to equate to around 70HRC from what I have had sectioned and tested. The nitrided layer is of no value unless the white layer is minimal.
Case hardened cams are great but such a pain to manufacture. Again the manufacture is critical, and many cut corners as I suspect was the case in the 70's that lead to the Tufftride cam for the MK3. There is a simple, but not cheap, way to avoid distortion and get a consistent hard case prior to final grind.
Most of the stellite weld rods will give 44-46HRC, but with stellite the hardness is not the whole story. If you use a welder to apply Stellite weld or other harder weld that is now available, ask for the rod certification and check it with the supplier. In the US and EU rods from a reputable supplier will be traceable.
Anyone out there with decent metal chemistry testing equipment might want to test a nitrided cam, I have tested a UK made version and the result was surprising.
There are still many case hardened cams still going in the Domi's, made correctly they are very good.
Stellite Delcrome is very good but it has some drawbacks, which more modern alloys can overcome in most applications.

If you want to cut something which is very hard, a soft wheel is often better.

madnorton - my photo is of a case hardened Atlas cam - it should be the same quality as the Domni cams.

ekdiehl - I don't think deflection was a problem with the street bike cam in the photo. It just isn't a perfect world and both lifters are not exactly the same - the wear patterns are not identical but both look OK.

So, on the subject of "reliable" cams, what can I expect for life & wear from a stock 850 cam that I bought from Norvil back in 2009? Bought followers too, which had to be lapped before they'd fit the cylinder bores. This is what came out of the motor after about 35,000 miles:

Yikes!- what did you run it on, castor oil?

I have a lot of experience with (car engine) camshafts and, TBH, my normal reaction to reports of "bad" or "soft" camshafts is "improper break in."
Further, I have run many flat tappet cam/lifter combinations with "modern" oils with no issue at all despite claims that traditional flat tappet engines require anti-wear additives when using current oils.

OTOH, "soft" camshafts certainly do occur. In fact, some years back, one of the major US makers of aftermarket performance camshafts acknowledged that they had produced a run of "soft" camshafts. Interestingly, I can't recall ever hearing of such a problem with a stock camshaft that came in a factory-produced engine. That would lead one to believe that the issue may be a combination of cam hardness/lift/spring tension that may exist in a modified engine. IOW, a cam material/hardness that works perfectly well with factory lift/springs may be "soft" with higher spring rates associated with increased lift/RPM/etc.

Bernhard said:

Yikes!- what did you run it on, castor oil?

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Close - Castrol GTX 20-50, per the owner's manual.

It's not the GTX, I've been running it for 40 years no problem.
Jaydee

this was a well known issue with small block chevys pretty much all through the very late 60s annd 70s.

MexicoMike said:

Interestingly, I can't recall ever hearing of such a problem with a stock camshaft that came in a factory-produced engine.

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I can't agree about the 750 cams not wearing out. My 750 Combat has just had it's third camshaft in it's 70k odd miles life. Both ones that wore out were original 1972 cams. One that the factory fitted and the second I fitted, that had been given me by a friend who got one from the factory under warranty in 1972 but had never fitted it to his Commando which he sold.

Early on in the bikes life I used various 20/50 oils, before switching to straight grade 40, usually Silkoline. The 40 seemed good but I was persuaded by people saying how good modern oils were to switch to Valvoline 20/50. After a few years of this the cam was worn. Obviously I have no idea if it was the switch to Valvoline that did for the cam but I have now gone back to the Silkoline 40 with me new AN cam and followers. Time will tell.

Ian

All of this scary stuff has assured that I'll do no exploratory surgery on my 850 as long as it continues to run as strongly as it does... Nor any 'spermentin' with new oils & methods of extracting more fleeting HP from the venerable old beast. If it works I'm not gonna attempt to unfix it better. I had no idea when I gave that guy my hard earned 500 dollars those many years ago these had so many short comings.
The research is invaluable though for when & if a catastrophe does strike. I appreciate this a lot. Have used a bunch on preventative maintenance aleady……….. 20w-50 GTX since '78 here also.

Maylar - your worn 850 cam is typical of some soft cams that were originally supplied. Norvil doesn't make their cams - the quality depends who they get them from (different suppliers). Read the "experience" at the bottom of my first thread - that cam came from Norvil.

Nortniggy - what do you mean when you say the combat cams "worn out"? Was there a measurable amount of wear? Or did they just look bad? When I say that early 750s cam were better I'm saying that they weren't problematic like the 850 cams with soft lobes that wore down to nothing. Its possible the combat cams came from a different supplier.

bill said:

this was a well known issue with small block chevys pretty much all through the very late 60s annd 70s.

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Really? I guess we were lucky. In all the SB chevy motors we worked on through the years, I never saw abnormally worn lobes when pulling an original cam from a stock engine. Admittedly, the engines we worked on were generally well-cared for to start with since we were a performance/competition shop so we didn't see neglected engines that didn't have fairly routine oil changes, etc.

jseng1 said:

Maylar - your worn 850 cam is typical of some soft cams that were originally supplied. Norvil doesn't make their cams - the quality depends who they get them from (different suppliers). Read the "experience" at the bottom of my first thread - that cam came from Norvil.

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I'm pretty sure (almost positive) that it is a Megacycle cam. I haven't been inside the motor since, but there's been very little change in rocker clearances in 10 years and there's certainly no little bits in my oil.

You might believe that if the cam is harder than the lifter, the cam would wear less than the lifter - but you might be wrong. Early Triumphs did not have Stellite tipped lifters and the cams used to wear like crazy. The joke was that if you replaced the worn lifters the motor became slower because the wear increased the timing duration.

jbruney said:

All of this scary stuff has assured that I'll do no exploratory surgery on my 850 as long as it continues to run as strongly as it does... Nor any 'spermentin' with new oils & methods of extracting more fleeting HP from the venerable old beast. If it works I'm not gonna attempt to unfix it better. I had no idea when I gave that guy my hard earned 500 dollars those many years ago these had so many short comings.
The research is invaluable though for when & if a catastrophe does strike. I appreciate this a lot. Have used a bunch on preventative maintenance aleady……….. 20w-50 GTX since '78 here also.

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I've got one of those bad MK3s. My thinking is that since the tappets don't ever require much, if any, adjustment and there is next to nothing on the magnetic drain plug....ride on in ignorant bliss!

Glen

jseng1 said:

Nortniggy - what do you mean when you say the combat cams "worn out"? Was there a measurable amount of wear? Or did they just look bad? When I say that early 750s cam were better I'm saying that they weren't problematic like the 850 cams with soft lobes that wore down to nothing. Its possible the combat cams came from a different supplier.

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This is the 2nd cam I removed. Worn quite a bit.

A mate of mine just refreshed the top end on his mk111 at 30,000 miles. He said his cam and flowers looked perfect.

Luck of the draw I guess ...