Worn PW3 cam

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Stellite has never been used to tip the followers, Delcrome has which was produced by the firm called Stellite way back who made various cobalt and iron hard faced materials and alloys and no surprise a material actually called Stellite. Current supplier of Delcrome is Delero in Europe, a subsidiary of a US company. Stellite and Delcrome are two very different materials, one iron based, one cobalt based, they can suit the same function but at different temperatures and Stellite has a better resistance to corrosion obviously. The other major major difference is cost, Cobalt is traded on the metal markets in lbs, not tonnes. Deloro also supply and apply coatings, and don't seem to need to advise coating Delcrome.
The answer to the cam failure is in post 1 on page 1 - the fact that the coated followers were not affected is typical of coating application. It will provide a very good sliding surface, but not one that can sustain impact as well - yes, it hard, but that is a function of the coating being able to reduce friction, the hardness of a coating when used on a cam is not what is being asked for. ask those that coat why this is and they should tell you, not sell to you - ever wondered what happens to the substrate under the interface of the coating when being applied. No doubt some can work out why the Delcrome will take a coating and survive and the cam does not. If you have a cam in constant contact with the cam follower then a coating would be ideal. The same problem has been around for ages in the grinding industry when grinding hardened bearing surfaces, but they will avoid it.
Beehive springs - excellent piece of kit, but you just can't use any beehive spring. The move from nested springs to single spring is the clue - ever wondered why there are two springs, not one when Norton could have used one, the second spring has another function other than get the poundage right to control the valve correctly. The low revivng engines we use are not even a challenge to spring makers these days.
It is also no secret who manufacturers these chill cast cams, do you honestly think that they buy just 50 blanks and grind them, no, more thousands at a time. Considering this is about one type of chilled cam issue, then further questions other than chill cast need to be queried. Considering the number of cams sold, inc PW3 that are fitted by many engine builders worldwide and home mechanics (some of whom are well over 26K miles on there PW3's) would quite clearly indicate that there is not an issue with the chill cast cams. Those that retail PW3 cams, maybe a surprise to some, but actual sell more than one every now and then. If there was an issue with chill cast, do you honestly think that any of them would carny on using it, no it would be substituted, so make your own minds up.
Coatings are excellent when used in the correct place, those that apply coatings should advise accordingly on application and suitability of base material and its pre-coat state and post coat state.
 
Madnorton said:
Stellite has never been used to tip the followers, Delcrome has which was produced by the firm called Stellite way back who made various cobalt and iron hard faced materials and alloys and no surprise a material actually called Stellite. Current supplier of Delcrome is Delero in Europe, a subsidiary of a US company. Stellite and Delcrome are two very different materials, one iron based, one cobalt based, they can suit the same function but at different temperatures and Stellite has a better resistance to corrosion obviously. The other major major difference is cost, Cobalt is traded on the metal markets in lbs, not tonnes. Deloro also supply and apply coatings, and don't seem to need to advise coating Delcrome.
The answer to the cam failure is in post 1 on page 1 - the fact that the coated followers were not affected is typical of coating application. It will provide a very good sliding surface, but not one that can sustain impact as well - yes, it hard, but that is a function of the coating being able to reduce friction, the hardness of a coating when used on a cam is not what is being asked for. ask those that coat why this is and they should tell you, not sell to you - ever wondered what happens to the substrate under the interface of the coating when being applied. No doubt some can work out why the Delcrome will take a coating and survive and the cam does not. If you have a cam in constant contact with the cam follower then a coating would be ideal. The same problem has been around for ages in the grinding industry when grinding hardened bearing surfaces, but they will avoid it.
Beehive springs - excellent piece of kit, but you just can't use any beehive spring. The move from nested springs to single spring is the clue - ever wondered why there are two springs, not one when Norton could have used one, the second spring has another function other than get the poundage right to control the valve correctly. The low revivng engines we use are not even a challenge to spring makers these days.
It is also no secret who manufacturers these chill cast cams, do you honestly think that they buy just 50 blanks and grind them, no, more thousands at a time. Considering this is about one type of chilled cam issue, then further questions other than chill cast need to be queried. Considering the number of cams sold, inc PW3 that are fitted by many engine builders worldwide and home mechanics (some of whom are well over 26K miles on there PW3's) would quite clearly indicate that there is not an issue with the chill cast cams. Those that retail PW3 cams, maybe a surprise to some, but actual sell more than one every now and then. If there was an issue with chill cast, do you honestly think that any of them would carny on using it, no it would be substituted, so make your own minds up.
Coatings are excellent when used in the correct place, those that apply coatings should advise accordingly on application and suitability of base material and its pre-coat state and post coat state.
Click to expand...

A really big post saying absolutely nothing. What do you think the problem is?
 
It's not rocket science, when you apply heat to a material the heat will affect it, the result with coating is that any hardening will reduce back down the natural hardness range of the material, thus losing the support to the coating. The delcrome tip has a natural hardness range that even though it will drop back will still be in far enough in spec to operate and support the coating. The surface provides reduced friction, the underlying material takes the knocks.
As previously, coatings are excellent but must be used in the right place.
 
Madnorton said:
It's not rocket science, when you apply heat to a material the heat will affect it, the result with coating is that any hardening will reduce back down the natural hardness range of the material, thus losing the support to the coating. The delcrome tip has a natural hardness range that even though it will drop back will still be in far enough in spec to operate and support the coating. The surface provides reduced friction, the underlying material takes the knocks.
As previously, coatings are excellent but must be used in the right place.
Click to expand...

So, in a nutshell, you are saying the coating is at fault?
 
No, it should not have been used. Also can we all see all the report from the metallurgist?
 
Madnorton said:
.............. do you honestly think that they buy just 50 blanks and grind them, no, more thousands at a time ........
Click to expand...

I have no idea how you can substantiate that comment. Even my following comment is heavily hearsay and assumption!

I bought a PW3 from Norman White, one of the last 3 from a batch in his stock, I understood we were talking under 20 per batch, he said another batch would not be available for several weeks. The other authorised PW3 retailer at the time, Mick Hemmings, lets say had a bigger stock, maybe 30. 50 blanks at a time would seem to be practical. So who is getting these thousands at a time?

With choices of standard, 2S, 3S, 4S, 7S, PW3, Maney, various Norris, Webcam and Megacycle grinds, (and JSM grinds are as I understand based on various of those already mentioned) just how many people are buying Norton twin cams of any grind in 'large' numbers? My guess is it would take you over 40 years to sell the PW3s you had made by the thousands at a time!
 
Madnorton said:
No, it should not have been used. Also can we all see all the report from the metallurgist?
Click to expand...

I don't have it. I have seen it, but It's in the hands of the rebuilder. He will decide how and when it is to be released. Please explain to me how my cam lasted so long, as in much, much longer than the other bikes with failed PW3 cams if the coating "shouldn't have been used". The metallurgist said that the only thing that made the cam stay together so long was due to the coating!
 
Madnorton,
Are you thinking my springs had something to do with the problem? Comnoz
 
Nope, providing they are installed correctly, you have proved this yourself many times over. But there others out there some use that are not yours.

As for the cam blanks, they don't have a specific blank for the PW3 and another for the standard cam. they all come from the same blank, feel free to ask the manufacturer, I have. What numbers of cut PW3 cams are sold is different.

As why the cam lasted for so long compared to others, is a big assumption that all failed for the same reason, highly unlikely.
 
Madnorton said:
Nope, providing they are installed correctly, you have proved this yourself many times over. But there others out there some use that are not yours.
Click to expand...

Well, my springs, proven on the PW3 cam...Not really. Of the roughly 150 spring sets I have sold I only know of a couple being used on the PW3 cam. Ken is one of them.

The two failed PW3 cams I have here were not run with my springs. Beyond that, I don't know much other than they were used for roadracing and did not last a season -so anything is possible.

I do know that on my spintron there were three cams that I tried that had spring surge and bounce problems below 8000 rpm with any of the 5 different springs I tried.
The PW3 was one of them.
 
As long as I can remember, someone I know has always been dealing with this issue.
It's clear to me that Commandos eat camshafts. Stock / aftermarket, it doesn't seem to matter.

Many smart people have put a lot of time and effort into addressing this problem, But yet........
it still happens regularly.

That leads me to ask: Is it actually the cams themselves or an engine design issue?

If it was just a problem with the metallurgy, you would think that after 50 years, someone would
have it sorted out by now.
 
Mark said:
As long as I can remember, someone I know has always been dealing with this issue.
It's clear to me that Commandos eat camshafts. Stock / aftermarket, it doesn't seem to matter.

Many smart people have put a lot of time and effort into addressing this problem, But yet........
it still happens regularly.

That leads me to ask: Is it actually the cams themselves or an engine design issue?

If it was just a problem with the metallurgy, you would think that after 50 years, someone would
have it sorted out by now.
Click to expand...

I don't know that I would agree with that. I haven't had a cam failure since early 80's in any of my bikes -street and race.
I would suspect that the most common causes of stock cam failure is a poor choice of engine oil and springs that are used up.
I would suspect the most common cause of high performance cam failure is setup problems -including mismatched springs. Comnoz
 
Some bikes kicking about since the early 70's still have the original camshafts in and still look good. As for oil, could be, but I doubt it, though I am just about to find out when I get in the garage and remove my barrel. Most oils are adeqaute these days, thugh some are superior to others. It has been using cheap Tesco own brand 5W-40 full synthetic oil for 10 years. With oil this thin I do not let it warm up, just thrash it. The barrel is being removed as I was replacing the head gasket and noticed that I could see a good portion top ring on the left cylinder at bdc, it would appear that it has been like this since new as the bore and pistons are original.
Once of the biggest causes of engine failure I see is contamination by considerate owners, usually blast media, shot blast and vapour, some engines contain both. One so bad that the media had blocked the return from the sump to the pump!
The tolerances of the head need to seen to be believed, simple things like fitting new valve seats can catch you out, it ran fine with the old ones - don't assume it will with the new ones, the distance to coil bound even with a standard cam can be so easily eroded.
Considering there are some that have bikes that are still one owner and have covered over 200,000 miles, I don't think cam failure is common. This afternoon I was looking at PW3 number 12, fitted and used since 1984, and only removed to test another cam. It still looked untouched.
Seems like COMNOZ has done his homework on his springs, what he has found can be easily eliminated these days and not evenly remotely acceptable for a valve spring in any automotive engine today. Two identical springs to the eye can have totally different characteristics, one would work at 8k rpm and the other at 4k rpm. With a spring, it must be designed to do two things, one to do what you want it to do and the other is to design it to do what it wants to do naturally away from where what you want it to do.
 
So then are we thinking that wearing a lobe off of a cam is primarily valve spring related?
 
Cam manufacturers say its the low RPM that causes wear on the can nose because that is when the spring pressure exerts the greatest force on the cam tip. Wear on the nose is not caused by too weak of a spring (a weak spring causes loft/bounce/wear AFTER peak lift - not on the nose). Elevated spring pressures exacerbate wear at low RPM and 850s are low/mid RPM grunters (especially single carb bikes). The conical springs used in Full Auto’s bike exert about 25% more spring pressure than stock. The increased lift of the PW3 raises the pressure on the nose even more. If Full Auto wants a longer lasting cam then he'll get it with hardwelded lobes, less lift and spring pressures closer to stock. Racing spring pressures for a single carb 850 make no sense at all. Full Auto's cam checked out fine for hardness. He uses good oil. The problem that still remains is the elevated spring pressures - a simple problem to fix. So why not address it?

Take a good long look at the photo below of typical stock Norton cam wear - caused by normal spring pressure at low/mid RPMs where city street Nortons spend so much of their time.

Worn PW3 cam
 
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^ Makes sense to me.
EDIT:

Hold on a minute.

comnoz says: "... a poor choice of engine oil and springs that are used up."
Weak Springs?

jseng1 says: "Wear on the nose is not caused by too weak of a spring...".

Which is it? am I missing something?

I have wore out two 850 cams, (both at about 35,000 miles and stock springs).

That pic shows quite a bit of wear for normal use,
actually enough in my opinion to warrant it to be called a wearable part.


FWIW:
spintron has to be one of the coolest names for a machine - ever!
 
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jseng1 said:
Cam manufacturers say its the low RPM that causes wear on the can nose because that is when the spring pressure exerts the greatest force on the cam tip. Wear on the nose is not caused by too weak of a spring (a weak spring causes loft/bounce/wear AFTER peak lift - not on the nose). Elevated spring pressures exacerbate wear at low RPM and 850s are low/mid RPM grunters (especially single carb bikes). The conical springs used in Full Auto’s bike exert about 25% more spring pressure than stock. The increased lift of the PW3 raises the pressure on the nose even more. If Full Auto wants a longer lasting cam then he'll get it with hardwelded lobes, less lift and spring pressures closer to stock. Racing spring pressures for a single carb 850 make no sense at all. Full Auto's cam checked out fine for hardness. He uses good oil. The problem that still remains is the elevated spring pressures - a simple problem to fix. So why not address it?

Take a good long look at the photo below of typical stock Norton cam wear - caused by normal spring pressure at low/mid RPMs where city street Nortons spend so much of their time.

Worn PW3 cam
Click to expand...

Then how come they are failing with standard valve springs as well? The other local cam that failed was using standard valve springs. It did 1500 miles.
 
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Madnorton said:
Nope, providing they are installed correctly, you have proved this yourself many times over. But there others out there some use that are not yours.

As for the cam blanks, they don't have a specific blank for the PW3 and another for the standard cam. they all come from the same blank, feel free to ask the manufacturer, I have. What numbers of cut PW3 cams are sold is different.

As why the cam lasted for so long compared to others, is a big assumption that all failed for the same reason, highly unlikely.
Click to expand...

Only those cams sold new ground from chilled cast iron are coming from blanks, most of the rest are welded/reground donors, so, since you have asked you can tell us, who is buying thousands of Norton twin cam blanks at a time?

Newman cams make the PW3 for Hemmings/White and I guess after Mick retired those now sell through AN. I guess I also assume Newman make other cams for AN on chilled cast iron blanks, eg, standard, 2S, 4S. Thousands, i.e. multiples thereof, is a lot of cams!

The UK CRMC no longer has a 1300 twins class due to a lack of Norton twins racing, there are only a handful in French racing, similar in Belgian events, so not many of these cams are being pushed to their limits worldwide! Fullauto's bike clearly was not being pushed to its limits!

I assume my PW3 failed due to a) lack of oil at critical time, b) revving to 8K, possibly creating that critical time (but it ran for 26 races before failing!).

Solutions?, I have been through the oil feed to try to ensure better oil supply/flow. I replaced the valve springs even though testing showed no significant reduced pressure. I have changed oil, now Mobil 1 15/50. I have changed cam to a hard welded Webcam, which coincidently, does not want to rev to 8K!
 
This is a long thread and maybe asked before.
Are this engines runing at idle too much?

As I have understand it, the oil film will break down and metallic contact between the lifts and the cam will occur. This leads to wear on the camlobe. So maybe we should add this as a contributing factor.
 
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