Cam and follower tests.
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Brooking 850
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Great stuff Jim, that will put the cat amongst the woodpile!!!!
Regards Mike
Regards Mike
You're not right up there with the current trends in sarcasm, are you?
Matchless
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Jim,
What Rockwell hardness are standard followers? Also, would the definative test be a cold start every two or three hours for a week; if you had nothing better to do that is.
It's a pity there isn't enough room for a follower which can rotate like a BMW air head or a modern bucket & shim arranement. Or is there?
Martyn.
What Rockwell hardness are standard followers? Also, would the definative test be a cold start every two or three hours for a week; if you had nothing better to do that is.
It's a pity there isn't enough room for a follower which can rotate like a BMW air head or a modern bucket & shim arranement. Or is there?
Martyn.
Jim, I have been studying the design virtues of the unified twin (UT) engine lately (reprinted in the last 3 issues of "Jampot", the AJS/M club magazine). Maybe you have read it. If not, I would be happy to send you the articles. They are a contraction of articles first appearing in Real Classics [HASHTAG]#134[/HASHTAG] / 135, and [HASHTAG]#144[/HASHTAG] / 145 / 146. This UT engine has several design virtues of what the Dominator engine should have evolved into. One of the virtues is improved camshaft oiling: The camshaft sits in a trough of oil. I know this has been tried on Commandos as well. My question is, to which extent does lack of lubrication, or insufficient lubrication, or lubrication using super-hot oil, affect camshaft and follower wear? And why doesn't the trough design work in the Commando engine - or does it?
Both Norton and Matchless have obvious design problems when using solid followers (Matchless on their performance singles), where followers tend to dig into the ramp of aggressive cam lobes. I think the problem is similar with the Dominator engine - contact forces become huge and the lubricating oil film is penetrated.
My second question is therefore, what are the design challenges in constructing a lightweight roller follower?
https://shop.brutespeed.com/Comp-850-16-Hydraulic-Roller-Lifters-GM-SBC-LT1-LS1-Comp-850-16.htm
The rolling friction factor Crr is much, much lower than the gliding friction factor Crg and to me, a development in this direction is the obvious answer to abnormal camshaft and follower wear. Roller tappets also makes it possible to extract more power using a dedicated camshaft.
http://www.lunatipower.com/Tech/Cams/FlatTappetOrRoller.aspx
However, I admire your systematic research of the faults found with the stock design!
B.R.
Knut
Both Norton and Matchless have obvious design problems when using solid followers (Matchless on their performance singles), where followers tend to dig into the ramp of aggressive cam lobes. I think the problem is similar with the Dominator engine - contact forces become huge and the lubricating oil film is penetrated.
My second question is therefore, what are the design challenges in constructing a lightweight roller follower?
https://shop.brutespeed.com/Comp-850-16-Hydraulic-Roller-Lifters-GM-SBC-LT1-LS1-Comp-850-16.htm
The rolling friction factor Crr is much, much lower than the gliding friction factor Crg and to me, a development in this direction is the obvious answer to abnormal camshaft and follower wear. Roller tappets also makes it possible to extract more power using a dedicated camshaft.
http://www.lunatipower.com/Tech/Cams/FlatTappetOrRoller.aspx
However, I admire your systematic research of the faults found with the stock design!
B.R.
Knut
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SteveA
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Whilst other things may be of interest, I think we are going for a basic enquiry here. And a workable solution at reasonable cost.
Norton cam and followers, within certain limits, were fairly successful for 40 years. Now some failures are occuring that don't seem to follow the trend of that period. What has changed?
1. Design? No.
2. Manufacturing processes? Possibly, certainly we know manufacturers have changed.
3. Materials and hardness (hardening processes?), could be!
I think Jim is investigating 3 to address a workable, and sort of immediate, solution at reasonable cost based on refurb of existing components.
A good answer here gives those of us who might need it an available solution, and provides information to others on a way forward.
Even if a roller follower solution were viable, how many would opt to modify their motors to use it?
After one more race meeting this month I shall be opening my own motor with some trepidation!
o0norton0o
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The stock followers have their stellite pads attached by oven brazing. Sadly, some of these pads will eventually delaminate from the body of the follower and can do some serious damage to the bottom end. I had a follower lose it's pad while my bike was idling in the driveway last year. I heard the noise start, shut the bike off then went through the long process of pulling the top end apart to find the follower's pad detached, sitting on top of it's cam lobe. No damage! I got lucky as hell.
A norton friend of mine, just this previous weekend had one of his intake valves drop it's captured pushrod. All of a sudden he has a great amount of play in that valve train linkage. (I suspect he lost the stellite pad on his follower...) It happens often enough to be a flaw. He rode his bike home on one cylinder. I'd hate to see what his cam looks like now... (probably like Jim's cam looked)
All interesting stuff, but in this case, totally irrelevant.
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The original spec for the cam follower called for RHc 58-60
Of the ~ 100 cam followers I have checked, about 10% did not meet the spec, some by a large margin.
I suspect this has had a lot to do with cam failures over the years.
Deets55
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I had two cam failures in quick succession back in the early 80's and designed a tube with a cutout in the top to clear the followers that created a large trough to hold the oil after the first failure.
A short time later the new Weber cam that was in the trough failed also and I removed the trough and rifle drilled the repaired Weber cam cam for lubrication.
At the same time I also went back to a straight weight oil with a GM additive called EOS.
I had not had any more cam issues again -until this summer.
I chalked my two cam failures up to oil that was not up to the task. I had been using 10-40 Penzoil right out of the hose in the lube bay at the auto dealership where I worked.
I have since had a camera inside a running Norton motor and seen the blizzard of oil that convinced me that lack of oil was not likely. The camera was though a 3/4 "hole in the front of the case -pointed at the cam. The lens was coated with oil the instant the engine started.
Removing the camera and starting the motor made an immediate mess -with oil everywhere.
A roller follower could be built to fit in the Norton. I have seen some pictures of a set that was built by a fellow up in Canada several years back. They were quite limited in width and roller diameter. I have never heard anything more about how they worked out.
The biggest problem would be designing a cam that would work with the roller follower.
A hardweld cam or an iron cam are not a good match for a roller follower.
A case hardened gear steel cam would need to be built using a lobe design for a small diameter roller follower. This would be an expensive endeavor.
Then roller cams also have there own set of problems that would need to be worked through. These problems would likely be made worse by the small roller that could be used
-unless you wanted to re-design the barrel also.
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This is relevant, as I will not use the early design follower in my motor.
I do not want to chance loosing a stellite pad when I am 2000 miles from home. I don't usually have a chase truck handy like I did this summer.
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The followers went from design where the pad was simply brazed to the bottom of a flat steel body to a spiggoted design where the pad fits into a depression in the bottom of the steel body. This solved the problem of spitting the pads.
The change was made in the mid 80's as I recall.
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Yes all the OEM followers were non-spiggoted.
I tried the BSA followers in my street bike for a short time.
I used them in my roadracer for several years,
They also loose the pads occasionally, that was the only time I have lost a pad in my streetbike engine, luckily I was at home when it happened and damage was minimal. Of course it wiped out the cam -not the 312a grind which will not work with the BSA follower..
I went back to the same Webcam and Norton followers I was using before.
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Extract from an article "What's In a Camshaft". Autor Kris Wieber. The Shop Magazine, Dec. 2, 2009 :
Another factor that contributes to camshaft performance [life, added by KS] is oil. The lubricity of oil has been a recent issue for nearly all manufacturers of internal engine components.
"Motor oil has changed over the years, mainly with the removal of zinc-phosphates (ZDDP). The reason for the removal is because today’s new cars have roller tappet camshafts. Roller tappet cams do not require these additives that flat tappet (hydraulic or mechanical) camshafts need. Flat tappet camshafts require this extra protection because the lifter slides across the cam lobe. This metal-to-metal contact between the cam and lifter will not last long without this additive, especially during ‘break-in,’" says John Steely, sales manager for Howards Cams.
There are specialty oil manufactures, such as Brad Penn, that have this additive, he notes. But most of the common name brands (including Shell Rotella) no longer have zinc-phosphates at all.
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Is this common knowledge?
-Knut
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