Cam and follower tests.

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One problem with Norton lifters is their excessive mass.

Every time the lifter is accelerated from a dead stop to full lift – the resistant forces of inertia put strain on the hard pad and try to wipe it off the lifter body. The heavier the lifter – the more the strain – and it adds up over time. Triumphs and BSA lifters don’t have as high a failure rate of lifter pads as Nortons do because they only weigh about ½ as much as Norton lifters and so the strain/wear is reduced. Norton could easily have incorporated a lighter lifter ... they didn’t. But some of the high RPM Norton flat track tuners switched to BSA lifters.

Lightened BSA lifter below. BSA lifters were preferred over Triumphs because the BSA stems are stronger.

Cam and follower tests.


Lightening a Norton lifter has been done but its difficult. Here is what I used to do to stock lifters to help drain the oil in and above the lifter to reduce weight. Credit to Mic Ofield
Cam and follower tests.
whats the history of the modified norton follower in this picture? i have one single one in my collection and i wondered who did this mod?
 
Pity my OEM B40 cam follower lost its stellite pad then as otherwise it could be in my Norton, glad its not.
 
Since the conversation about cam/follower survival has drifted across the topic of oil-related factors and ZDDP, might as well bring surface finish into it too. The article linked below, by Prof G Blair & Associates, provides insight into 1) the importance of cam and follower surface finish, and 2) oil viscosity, and how oil film thickness varies as a function of camshaft angle, oil base ...

Lots of things to think about as new data is generated and we continue the discussion. It would be interesting to know the range of surface finish that occurs across the myriad Norton cam offerings out there as well as the surface finish on the followers. Note that a typical ground surface finish of 0.25 micron CLA, as stated in the article, is 0.0000393”.


I am not real sure what the Webcams are finished to, but the followers were finish ground with a 400 grit CBN stone -so around 65Um I would guess.

Lauri did say the cams finish would be suitable for a DLC coated follower, so that would indicate it was pretty fine.
 
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Jim, didnt you post a video on an oil additive showing its failure?
Regards Mike

That was STP's failure when used as prelube for a valve stem with minimal clearance.

It would have had nothing to do with ZDDP or antiwear properties. Just the fact that it was too thick to provide lubrication in a tight new valve guide.

ENGINE OIL ONLY FOR VALVE GUIDE PRE-LUBE. [At least for my head builds].
 
Instead of adding some kind of additive to the oil, why not just buy good oil with a high ZDDP content? That way you know the entire oil and additive ‘recipe’ is going to be good, and work together.

I can’t follow the logic that says we blokes in our sheds can mix a better oil than the top end reputable oil companies !
 
The oil you use probably costs a good deal more than other oils plus the cost of the little bottle of zinc poop. For most of us oldsters the cost
of oil today is unbelievable.
However, the cost of our bikes is equally beyond what we would have ever paid so, as per your policy, false economy using less than premium oil.
Maybe it doesnt matter, in which case you can simply say better safe than sorry.
 
Instead of adding some kind of additive to the oil, why not just buy good oil with a high ZDDP content? That way you know the entire oil and additive ‘recipe’ is going to be good, and work together.

I can’t follow the logic that says we blokes in our sheds can mix a better oil than the top end reputable oil companies !

Since when have oil companies been reputable? You must have different standards to me.
 
I think there needs to be a C.O.C. certificate added to the spiggoted lifters being sold lately. This is relevant in this discussion on the Norton type lifters. In comnoz's case as well as fullauto's who both do high mileage and use correct oil. One soft lifter takes out the cam. The $1000 question is why was there one, that was soft. Certificate of Conformance with RC values added. A German knife company Puma puts a Rockwell indent on all their knife blades to proof them. IMHO
Cheers,
Thomas
 
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Hi Jim
Very interesting subject you got going here, I am keen to see the results as I have had problems with Manx Cams and followers over the years with heavy wear.
Had no problems with the original Norton cams but thought I would fit new ones and then the problems started, tried three different after market cams and follower sets.
Now running a heavier oil with high Zinc load, and seem they seem to be holding up. After looking at your last post hardness could be one of the problems I am seeing.
I did have them tested at one stage but I have lost the data, funny thing is everyone of the old guys I asked if they had any failures, said no.

In your videos I note the wear patterns are not a full width it looks as if the cam is not ground square to follower but at full lift it appears ok?
The Manx cams and followers have a full width witness marks straight from start up?

Burgs
 
Hi Jim
Very interesting subject you got going here, I am keen to see the results as I have had problems with Manx Cams and followers over the years with heavy wear.
Had no problems with the original Norton cams but thought I would fit new ones and then the problems started, tried three different after market cams and follower sets.
Now running a heavier oil with high Zinc load, and seem they seem to be holding up. After looking at your last post hardness could be one of the problems I am seeing.
I did have them tested at one stage but I have lost the data, funny thing is everyone of the old guys I asked if they had any failures, said no.

In your videos I note the wear patterns are not a full width it looks as if the cam is not ground square to follower but at full lift it appears ok?
The Manx cams and followers have a full width witness marks straight from start up?

Burgs

Yeah,
I'm not sure if the follower was off a little bit or if the wear pattern is due to cam flex.

I have seen this before and since both followers were ground on the same fixture I suspect it's more due to cam flex. It always seems to be more evident on the RH followers.

I didn't attempt to correct it as I wanted a bit of "worst case scenario" to see if the follower showed distress.

In my new engine I have moved the cam bearings inboard -right to the edge of the lobes after eliminating the tach drive gear. I was hoping this might help make the contact more even.
 
Yes cam flex could certainly be a cause, making the moment arm shorter will help.
I guess when you moved the bearing in on the timing side you kept the distance to the sprocket the same as original so as not to load up the drive end of the cam.

Burgs
 
Since the conversation about cam/follower survival has drifted across the topic of oil-related factors and ZDDP, might as well bring surface finish into it too. The article linked below, by Prof G Blair & Associates, provides insight into 1) the importance of cam and follower surface finish, and 2) oil viscosity, and how oil film thickness varies as a function of camshaft angle, oil base weight, and oil temperature.

Lots of things to think about as new data is generated and we continue the discussion. It would be interesting to know the range of surface finish that occurs across the myriad Norton cam offerings out there as well as the surface finish on the followers. Note that a typical ground surface finish of 0.25 micron CLA, as stated in the article, is 0.0000393”.

Thanks for posting the link . Used to be said that a rebuilt engine with a new cam and followers should never be allowed to idle as they need to 'work harden' . What might be the case is that the two surfaces are polished in the critcal first start up if the engine is not allowed to idle
 
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Yes cam flex could certainly be a cause, making the moment arm shorter will help.
I guess when you moved the bearing in on the timing side you kept the distance to the sprocket the same as original so as not to load up the drive end of the cam.

Burgs

Yes, I put needle bearings right next to the lobes and a ball bearing next to the sprocket to support the RH end and control the end play.
 
I am not real sure what the Webcams are finished to, but the followers were finish ground with a 400 grit CBN stone -so around 65Um I would guess.

Lauri did say the cams finish would be suitable for a DLC coated follower, so that would indicate it was pretty fine.
Per the table below, with your 400 grit CBN stone you should be right there in the same ballpark quoted in the Blair article for a CLA roughness of 0.25 micron give or take a bit.

Cam and follower tests.
 
"Yes, I put needle bearings right next to the lobes and a ball bearing next to the sprocket to support the RH end and control the end play."
Jim, Your bike is highly modified (and I admire that) but what about us low life's who just rebuild to factory spec.
What we need to see is a stock high mileage cam and lifter set up with Rockwell C testing on both Followers and Cam that have stood the test without wear. What can we derive from that correlation. I am really confused why one lobe takes a dump.
Cheers,
T
 
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