Marine
This may be too obvious but, you did use the correct 1/4" BSF SHCS that came with the E/I kit. These kits come with both BSF and UNF bolts for English made cams (BSF) or US made cams (UNF). The difference is only 2 threads per inch. This will allow the bolt to screw in partially before you would feel binding if it is placed in the wrong cam manufacturer. It’s just a thought as to why it might have cracked at this location. Megacycle makes a good cam. 560-NSS comes to mind.
Regards,
CNN

It wasn't the threaded part, but the tapered end which split all the way back to where the threads start. The retaining bolt screwed in all the way with no binding up.

Marine
So the crack developed at the tapered. That's too bad. With cast iron it is no easy fix without applying heat. A speedy sleeve comes to mind but it doesn't address the crack. Nothing short of splitting the crankcase halves again and changing it out.
CNN

Btw, this is the 2nd cracked cam end I've read about on this forum, joining it about 2 yr ago and seems I remember a couple more identical fractures mentioned in horror on BI, INOA and NOC lists some years ago. Sometimes it helps to know it ain't just you being picked on by flying fickle finger of fate. Also I've gotten some encouragement to face my own travails reading of others facing total tear downs no fault of their own - yet nothing for it but biting bullet to dig in to get the suffering over with over many weeks or months or seasons or years - if still Cdo carrot enough left to cause ya to do so. Stuff like this in distance past is why we still hear so regularly of barn finds to restore.

Mmm Steve
My curiosity perked on this as well. I know the taper on the original contact breaker points were steel and the Boyer E/I magnetic rotor is steel. Yet my Pazon Surefire magnetic rotor is made of aluminum. Would there be enough expansion rate difference between the two dissimilar metals to cause the chilled cast-iron cams to crack in this area when things start to warm up? Who knows?
CNN

Thanks for the kind words Hobot... But hey my glass is half full.. Doing it now will free up time in the future for more happy days riding.. And hopefully in the warmer months... S..t happens. Regarding the expansion rates of different materials,,,,, who knows. Perhaps someone with the knowledge can put fears to rest?

I sold a new BSA Regal N.A. chilled iron cam to a friend. The exact thing happened to him. His split right on the casting mold parting line. It took a long time but BSA regal warrantied it (refund). Their was claims of over tightening blah blah blah etc.
Well I took a new cam AA bolt and using a torque wrench I tightened a bolt into a steel cam until it broke off....about 14 ft lbs. So you can imagine how little torque will break one of these iron cams since my friend did NOT break his bolt....

IMO these cams are not worth using and I'd rather have an old steel cam welded and reground. One of these days I am going to steallite one myself and grind my own...

FWIW Norvil claim they sell steel stock grind cams. I have only gotten their domi 2S, commando 4S and domi 7S and they were adequately hard.
I would do a web regrind or the mild megacycle. I had heard megacycle will even do a stock grind to order????

Well its another threaded hole I'll not put any loctite in to build up wedging loads.
Al expands more than steel so the Al trigger tapper on the outside should not add any stress, just the bolt inside by torque or its own thermal expansion. Some mechanics just get luck of the draw on random manufacture faults and half the relief of these forums is to get helped out of mood of why me depression.

Until 2009 every winter recovery meant painful cold will power endurance test vs desire to have a ride when not so bad out till gets so hot its more injurous than the cold. This time last year was 1/3 the way through Trixies 4th rebuild since '06 and still remember pressing myself to do something every day till too chilled. Wes was here today on his scooter helping me tip over Ms Peel outside and reminded me in his annoyingly truth crudgemongeon way, after listing all the places I've not yet road, " ya know Steve you've missed out years at a time fussing with Commando's"
Trixie took 9 mo's d/t most of it being nearly freezing with short mild intervals.

Spoke again to Andover regarding the cam. They are now going to put a warning in with all new cams regarding tightening down on the cold cast. They also gave me a very good discount on a new one.. Just got to rip it down now. Oh the joys of norton ownership . Love em...

marinecommando wrote: Just got to rip it down now. Oh the joys of norton ownership . Love em...

I know that feeling and every time that I do it, I think "This time it's going to be really right."

Well at least we can do it ourselves! Don't have to put up with some spotty youth plugging in his computer and telling us so and so sensor is not working... The only ECU is between your ears.

Hi Marinecommando, sorry about , but thank you for that info, I was just fitting a new Andover cam last saturday when I saw your "beware", and so I was used to use air wrench on that nut, that time , i will wait the rear wheel will be on the bike and like before put the fourth gear on , applied rear brake , and torque that nut........Marinatlas.

If you had one of these that cam change would be done in the bike and under an hour!






And while it's apart add this..