soft cam

hobot said:

What about nitriding as done to crankshafts and such. Polished up of course.
There is micro polishing services but don't know if worth it or not in lifters/cam.

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soft-cam-t9293-30.html#p102532
aren't cranks en40 ?
per materials literature for en32, nitriding is ineffective
then why would you consider it?

WEAL Norton said:

I did not expect that our homemade lifters would give problems. But after a quick check on the valvedrive rig with an ordinary 2S cam we had no problems up to 4000 (8000 at crank). So the problem seems to be generated by the much faster acceleration and bigger lift of our homemade cams. The valves have only 7mm stems (inlet/exhaust) and thinner valveheads as well. Pushrods are STD but rockers are lightened so weight is not an issue. The 320 degr cam might be a bit over the top as the engine coughed a bit up to 2000 revs as the charge was riched very much by blowback - the fog behind the carb disappeared at about 2500. Maybe I can cure that with longer inlet tracks...

I had several cams casehardened in the past after grinding my own profiles - never had a problem so far. I do have a cam in the shelf (might be a Megacycle - I don´t know) which did not respond to case hardening. Everything on the cam went black and hard - EXCEPT the lobes!!! They stayed shiny yellow - looks like stainless steel. They are still soft, could be machined with a file! So this cam must have been made by friction welding different materials ... I didn´t dare to put it in an engine but maybe the comparatively soft cam might work good with a very hard follower.....
Any thoughts on this????

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Since I had considered repairing a few cams myself with stellite....I'm no expert in this area but, some after market cam repairers supposidly use stellite hard facing/welded process. According to the materials literature I've read this only yields mid to high 40's RC depending on the grade of stellite.
They would then not respond to EN32 case hardening on the lobes :roll:

I regularly use welded cams from Web-cam, I have had very good results. They test soft on the base and generally around 50 on the weld. If you try to harden them the base will get hard but the weld will get softer. Jim

They must be using stellite 12 since, type 6 & 12 would typically be used.
6 is 40-45RC and 12 is 45-51 RC.
I was going to go with 12 for my lobe reconditioning.

Dave

When I got the cam back from hardening everything was black - except the lobes - they were green! So the immersion in the saltbath where the carbon is applied caused some chemical reaction. However it was easy to wipe the green stuff away. I don´t know if this cam was stellited as the material is all the way around the lobe and the base as well.....
Maybe I should check it properly for hardness and try it in my 750 - I always wondered what that cam will do.

Cheers

hartmut

comnoz said:

I have a nice hardness tester and over the years I have tested a lot of Norton cams. Both the ones that were supposedly good and the ones that were supposedly soft like the MK3 cams. Both good cams and failed cams.
Generally I have seen hardness range from about 50 to 65 and had pretty much decided that the soft cam deal was just a wives tale.
However today I pulled an old Mk3 motor apart that had a hole in the cases and had been laying around for years. The cam was showing some wear but probably usable. I put it in the tester and wow. 35RC. Just to see if I was doing something wrong I pulled out a pile of cams and saw the normal 50 - 65 on the lobe but I must say- I found a soft one. Jim

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I waited for a while to reply to this thread to give myself time to scour the NCNOC archives for an article related on Norton parts and the poor hardening processes. Look at below thread on page 13. Nick Wiltz, a good friend in those days, wrote this article 25 years ago. Nick at the time was a recent graduate of Washington State University with a degree in Metallurgical Engineering. He Nitrided several "new" camshafts for Bob Raber (San Jose Norton shop) that tested soft. Norton Notice Issue #98 June 1986.

http://www.nortonclub.com/Newsletter/vo ... -lores.pdf

Even hardfaced cams seem to beat themselves up on a Nort. After a season of racing they would look hammered & filled. That's one reason I went to so much trouble setting up radiused cams with the lightweight radiused lifters. Both the lifter and the cam being curved makes a big difference when it comes to longevity.

Jim S

Responding to Jim's post:
You sell BSA lifters as a kit I think. Im not a racer nor a machinist, but
I used to work on BSA Triumph a lot and I cannot say I remember the
cams being a problem in terms of rapid wear. The lifters seem tiny
compared to Norton too. It was a long time ago but that is how
I remember it. Also know that very few riders back then
put on a lot of miles per year. In fact most rarely did 10k.
That they pounded the snot out of them was true though.
So I suppose my question is how do you find the wear rate of
BSA-type followers to be in Norton service?

I find the wear rate to be much improved with the BSA type lifters - to the point that you can forget about it. This is one of the best upgrades you can make on a Norton. Everyone complains about cam/lifters problems on a Nort and concern about keeping them oiled well etc. All those problems disappear with the lightweight radiused lifters. But they require special cam profiles to work. You can't use them with Norton cams. This means that you have to do a bunch of research & calculations to find what you want. I've already done that and the results are at:

http://www.jsmotorsport.com/technical_CamLifters.asp

I cant' tell you exactly why the wearing problem is solved - but much of it has to do with the reduced weight and the radiused surface as opposed to the high stress flat lifter surface. There is no reason that we should have to run those big heavy lunks of cast iron as supplied on stock norts. When you get rid of the weight you get rid of the friction.



The only problem the dwindling supply BSA lifters.

For those who are trying to create cam profiles that are off the charts, the only solution would be to go to a roller cam and for that you would have to adopt the Harley dirt track racer setup - good luck. I don't think its necessary- the radiused lifters extend the life of the cam and allow for higher RPMs as it is.

Jim S

I packed and sent my old MK3 cam your way the other day, here's a picture of what it looks like after laying around in a box of parts for 20 odd years. i can see in your other posts that your super busy with the twingle and life in general, so when ever you get around to checking the hardness of this thing, it's fine by me. thanks in advance Cj

cjandme said:

I packed and sent my old MK3 cam your way the other day, here's a picture of what it looks like after laying around in a box of parts for 20 odd years. i can see in your other posts that your super busy with the twingle and life in general, so when ever you get around to checking the hardness of this thing, it's fine by me. thanks in advance Cj

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Got your cam and checked it. Found a minimum of 54RC on the base, 68-72 on the lobe faces and 64 on the peaks of the lobe where there was some wear. I didn't figure in the correction for diameter which would increase the base hardness numbers a bit. I would not call this a soft cam by any means. Jim

jseng1 said:

The only problem the dwindling supply BSA lifters.
Jim S

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What's the difficulty level on reproducing them?

by comnoz » Thu May 05, 2011 2:36 pm
"Got your cam and checked it. Found a minimum of 54RC on the base, 68-72 on the lobe faces and 64 on the peaks of the lobe where there was some wear. I didn't figure in the correction for diameter which would increase the base hardness numbers a bit. I would not call this a soft cam by any means. Jim"

WoW that's interesting news, thanks a bunch Jim! so I should probably think about a different reason why the motor ate itself. Cj
P.S. Is it of any use to you as a core?

cjandme said:

by comnoz » Thu May 05, 2011 2:36 pm
"Got your cam and checked it. Found a minimum of 54RC on the base, 68-72 on the lobe faces and 64 on the peaks of the lobe where there was some wear. I didn't figure in the correction for diameter which would increase the base hardness numbers a bit. I would not call this a soft cam by any means. Jim"

WoW that's interesting news, thanks a bunch Jim! so I should probably think about a different reason why the motor ate itself. Cj
P.S. Is it of any use to you as a core?

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The damage looks like it was just 1 lobe. Did it have a lifter pad come off or maybe a broken lifter ? If not it was likely lubrication failure.

With the rust pitting on the bearing journal I am afraid this cam is just scrap metal. Jim

I can't see clearly the center of the cam between the intake lobes, in the first pix it appears as if there was accommodation for a raised section for early type breather. I have not seen these type cores in 75's... the 74 and 75 there was a smooth section between the intake lobes. It makes me wonder if it actually is a genuine 75?

by comnoz » Thu May 05, 2011 4:02 pm
"The damage looks like it was just 1 lobe. Did it have a lifter pad come off or maybe a broken lifter ? If not it was likely lubrication failure. "

Again Jim Thanks! I haven't even started it yet, so now I'm really doubting what the PO told me. Not that he was trying to decieve me, I think he just didn't remember from all those years ago. At 2500 bucks i still think it was a good deal. just now I'm thinking i should take it apart instead of moving forward to get it started. I've still got to clean the gas tank, get the brakes working and check for a spark and now really check the oil pump volume/pressure when it does fire up. Cj

by dynodave » Thu May 05, 2011 5:44 pm
"I can't see clearly the center of the cam between the intake lobes, in the first pix it appears as if there was accommodation for a raised section for early type breather. I have not seen these type cores in 75's... the 74 and 75 there was a smooth section between the intake lobes. It makes me wonder if it actually is a genuine 75?"

Thanks dynodave it makes me wonder too, The previous owner said that the guy he bought it from (one of his friends)had put a "hot Cam" in it one with "Welded up lobe profiles". That's apparently not true, well the cam not been welded. he went on to say that he smoothed out the nicks in the cases before he put it back together. Really thinking that i should pull it apart. I'm just not really set up in this garage here. Live in Gov. housing on base here at Naval Air Station Patuxent River. I've built a bench and have some tools here, but concerned I'll be unable to devote enough time for a complete tear down and rebuild (have 6 small kids --9yrs old down through 1) . On the other hand if i get it started and then it has oil pressure problems or if PO didn't get it back together right I could be looking at a full tear down and rebuild anyway. Hmmm... JS Motorsports cam and lifter kit is looking real good about now.....still waiting on our tax refund to come back....nawh... my wife would kill me, think i gotta go with what i got and Check Oil Pressure.Cj

It is definitely not a MK3 850 cam. It is an old case hardened 2s cam [combat]. No signs of being welded. Jim

Thanks Jim, Don't waste postage on just pitch it. Cj