Worn PW3 cam

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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.
So, the cams are failing because, all of a sudden, our cams are failing because they are idling too much? Really?
 
Unless I have missed it in a previous post, I cannot recall Fullauto telling the nature of the wear, be it a scuffing /wiping/smearing condition, or rather a surface pitting/erosion type, and where on the lobe(s) the main wear area is located.
 
So, the cams are failing because, all of a sudden, our cams are failing because they are idling too much? Really?

I’m no expert at cam wear. However, after being a member of this excellent site for a few years, it is widely known that our Norton engines should not be idle more than necessary due to the lack of maintaining the oil film between the lifts and cam.

The question is how much this contributes to the overall wear of the cam. I do not know, but I am convinced that this is contributing.
I do not allow my Norton to ideling more then necessary.
 
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Ohh no, I have just removed my barrel and after years of using supermarket cheapest full synthetic 5W-40 oil, idling at low revs cutting through miles of rush hour traffic jams for the past 3 years at low revs as well, it would suggest that the standard EN steel cam would be a nice piece of tube - strangely not, it is not perfect, the right hand exhaust lobe has started to wear and so has the follower the other lobes are like new and the followers show only the normal pattern, these were refaced when the cam was put in 18 years ago. This would suggest that the oil is not blame, nor are low revs.

It is well known premature cam wear has occurred on steel and chill cast cams, made even more frustrating by the like of my cam that 3 of the 4 lobes are like the day it was installed. If it was contamination from above then the adjacent lobe and follower would be affected, it's not, so that theory is discounted. If it was the material then more than one lobe would be expected to fail, they haven't So the oil, low revs, contamination and material are off the hook.

Springs, the head was replaced in 2016, new valves and standard springs were fitted, if it was the springs then surely it would affect another lobe, again it hasn't so I doubt the springs but not entirely because of what I found, the remaining valve tips show wear on the tip where the adjuster runs, the valve tip on the worn lobe side shows nothing not even any rubbing. It looks very much like there has been insufficient spring pressure on this exhaust side, and thus the reason for not even a rub mark - could this be the reason?

Installation, possibly - being a head fitted with standard items and running on a standard cam I did not check for coil bound, but being on the exhaust side the remaining spring travel at full lift is more generous than the inlet, so I doubt this is a factor, as I would expected similar on the opposite side, also an imprint or wear mark on the valve tip.

I am now suspecting spring or things that can affect spring pressure and will check a few more things on that failed lobe side, valve stem collet recess height, fitted valve seat height etc and compare it to the good side.

This leaves very few possible causes of premature cam wear, irrespective of material and type, loss of lubrication, installation, dimensional changes relating to the head, machining and fitting of valve seats.

Strangely, I am now in the position that I can test a few things, and thrash the bike to Austria later in the summer, or fit my spare engine that is built up with standard chill cast cam and test that.
 
With over ten years use, and one worn lobe, the rest perfect, then whether it has or hasn't adeqaute zinc, it has worked. the original bores fine - just odd shaped and believed to be like that from new, and the blow by on the original pistons is minimal despite the odd shaped bore. The piston skirts are like the day they were fitted even after 37K miles - guess what I'll be using in future.
 
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.

And as I understand it, the primary role of zinc is to provide protection exactly when the oil film has broken down and metal contact occurs.

Personally, I’ll be continuing to ensure I’ve got zinc in my oil.
 
Madnorton, your post kinda illustrates what someone said earlier about oil threads.

You are taking your evidence as proof that zinc doesn’t matter.

A zinc believer however, would argue “yes but the cam would’ve lasted even longer IF you’d had zinc in there”!

The truth is of course, that unless two engines are built to identical specs and ridden side-by-side in and identical manner for 10+ years, there’s actually no way of proving either side.

It reminds me of a the religious sect leader who predicted the end of the world and told his followers to pray. When the end of the world didn’t come, all none believers saw it as proof the sect leader was a fruitcake. And the sect was nonsense. But the sect members saw it as proof that their leader had saved the world, and of the power of their prayers, it reinforced their belief massively!

What’s my point? Just that I don’t think anyone ever changes anyone else’s preconceived opinions in these threads.

Jus’ sayin’
 
Here's an opinion- as we age the stubborn belief factor goes up. Maybe that is why it is easier to learn when we are young.
We are mostly oldies on this site, so lots of stubborn.
A simple check for seat pressure on the spring above the affected cam lobe might give some good info.
We found that the stock Vincent valve springs dropped from 105 lbs installed seat pressure to as low as 40 lbs after a few thousand miles. It didn't matter if you were happy with an 85 mph top speed and never revved above 4000
The solution was to have RD build springs for us. Proper top speed returned.
Perhaps stock Norton springs are coming from the same UK shed as our stock Vincent springs come from?

Glen
 
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I used to live just round the corner from Charlie Barnes, who is very well known as a master Triumph Trident motor builder. When I had my T160 I would go over to Charlie’s and learn all about, what seemed to me, a quite complex motor. What Charlie was adamant about was the use of oil with high zinc content. He really emphasized that I use oil specifically formulated for V-twins as he had seen a few motors where the cams had failed due to the use of modern oils with low zinc content. Coincidence?
 
..... the remaining valve tips show wear on the tip where the adjuster runs, the valve tip on the worn lobe side shows nothing not even any rubbing. It looks very much like there has been insufficient spring pressure on this exhaust side, and thus the reason for not even a rub mark
This is interesting.
 
I used to live just round the corner from Charlie Barnes, who is very well known as a master Triumph Trident motor builder. When I had my T160 I would go over to Charlie’s and learn all about, what seemed to me, a quite complex motor. What Charlie was adamant about was the use of oil with high zinc content. He really emphasized that I use oil specifically formulated for V-twins as he had seen a few motors where the cams had failed due to the use of modern oils with low zinc content. Coincidence?

That’s why I use this: https://www.redlineoil.com/20w60-motorcycle-oil

2125ppm zinc in the one I use.

It’s availble in weights from 0w40 to 20w60.

Being an old air cooled motor that was “machined to the nearest inch” and one that tends to get caned frequently, I use the 20w60.

Not preachin’ jus’ puttin’ it out there...
 
Zinc, without it the theory is that all the lobes would have suffered, 3 on my cam are like the day they were installed, 1 is not. Had they all worn to the same extent then I would consider oil and zinc content a possibility. Like FA said, interesting. Something is telling me that this is more than the cam material, zinc, or even installation. The other point to note is that the valve tip on the worn lobe side is totally unmarked.
In the cases that are known on here it seems to have happened to experienced engine builders and home mechanics, both having premature failure and both having good results, this would also suggest that the cam irrespective of type or material is not the culprit - it just so happens to be the result. Just need to find the cause, in the past when engine builders have seen the worn cam it was most probably considered the problem and swapped out and nothing else looked at, hopefully now when an odd lobe is worn, the whole system on that lobe can be more closely inspected - someone is bound to spot something!
This is not a case of chill cast cam versus steel it is about premature failure, with 4 lobes damaged more easily to diagnose, with just one lobe then the options seem to be coil bound or springs, if there is problem causing failure then it does not matter a jot what cam you have fitted.
The Vincent spring theory is plausible, but then again it would have happened to more than 1 spring set out of the 4.
 
Hi, it's quite easy to check your 4 valves springs , and see if one had lost some stiffness.........
 
Zinc, without it the theory is that all the lobes would have suffered, 3 on my cam are like the day they were installed, 1 is not. Had they all worn to the same extent then I would consider oil and zinc content a possibility. Like FA said, interesting. Something is telling me that this is more than the cam material, zinc, or even installation. The other point to note is that the valve tip on the worn lobe side is totally unmarked.
In the cases that are known on here it seems to have happened to experienced engine builders and home mechanics, both having premature failure and both having good results, this would also suggest that the cam irrespective of type or material is not the culprit - it just so happens to be the result. Just need to find the cause, in the past when engine builders have seen the worn cam it was most probably considered the problem and swapped out and nothing else looked at, hopefully now when an odd lobe is worn, the whole system on that lobe can be more closely inspected - someone is bound to spot something!
This is not a case of chill cast cam versus steel it is about premature failure, with 4 lobes damaged more easily to diagnose, with just one lobe then the options seem to be coil bound or springs, if there is problem causing failure then it does not matter a jot what cam you have fitted.
The Vincent spring theory is plausible, but then again it would have happened to more than 1 spring set out of the 4.

You are assuming that distribution of oil over your cam and lifters is uniform. There may well be more than one factor at play but you are going against the advice of all major oil companies about the needs of flat tappet engines. As a minimum you need 1000ppm . I would not feel happy putting additives in a multigrade lest it upset the existing chemical soup . Full Auto uses oil that has around 1500 and Eddie's Redline is 2200.
 
In both of my cam failures, each time it was the L.H. exhaust lobe that was worn through,
the other lobes and lifters looked fine.

With the same damage in the same location within pretty much the same miles,
It made me assume that something in that area of my engine wasn't lining up quite right
and causing the "premature" wear.

When one lobe is shot and the other 3 are fine, it's pretty tough to blame it on the oil.
 
In both of my cam failures, each time it was the L.H. exhaust lobe that was worn through,
the other lobes and lifters looked fine.

With the same damage in the same location within pretty much the same miles,
It made me assume that something in that area of my engine wasn't lining up quite right
and causing the "premature" wear.

When one lobe is shot and the other 3 are fine, it's pretty tough to blame it on the oil.

LH is that drive side?
 
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.

Yes the cams can fail both with normal spring pressure and racing spring pressure. But at low/med RPM - jacking up the pressure will just make it wear out sooner.

Low RPMS put the most pressure and wear on the cam nose. Higher RPMS accelerate the lifter up the opening ramp so it throws itself over the nose with less pressure (as per Snotzo's description). This is called "loft" and the lifter may not even touch the nose if the RPM is high enough - the lifter will come back down on the closing flank of the cam. Nascars get more power with more lift this way. The greatest danger of weak springs is that the valve will come down so hard and fast at high RPM and bounce so high that it will tangle with the opening intake valve and destroy everything. This is really what you have to worry about with weak springs. Usually (if you're lucky like worntorn) - the motor won't rev high with weak springs.
 
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Can we do a poll on here? Is the LH ex lobe really the comon culprit (or victim)?

Does the crank not throw as much oil at that lobe?

Is there something else it could be?
 
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