K2FC cam variation

I would not be happy with that. Equally I would not be in a rush to try to solve it by stoning the cam ring. Do plenty of reading up on the subject.The fitting of the bearing insulator paper can affect the timing and its also posibble to pack the cam ring on auto advance mags.

I have run my Dommi 99 for many years with a K2F with disparatecylinder timings with no apparent adverse consequence. I can't rememberthe exact figure, but seem to think it was 5 degrees between cylinders. The last time I tried (15 years ago?)cam rings were not available and there was no cure for unequal wear, it was just something that was 'accepted'. As regards acceptability, that is a matter of choice. If you can find a better solution that would be good, but if you can't I would still be happy to run as it is, particularly if no pinking occurred. I hope that helps, Regards, Howard

Previously ian_richtsteig wrote:

Can anyone advise what is an acceptable variation betwen the two cams of a K2FC mag for a 650SS.

I've just set my timing and to get firing at 29 degrees btdc, the left cylinder had to be set at 32 degrees and the right cylinder at 26 degrees btdc.

Is a 6 degree variation acceptable or do I look for a new cam ring?

regards

The advice was always NEVER split the difference. Set the most advanced cylinder to the correct timing and let the other be retarded by, in your case, 6 degrees, so 29/23 would be what you want. 6 degrees difference is about as much as you would/should tolerate. I would ideally want it down to about 2 degrees so see if you can find a decent cam ring.

Hi Ian

Gordon is right about not splitting the difference, better to have one running retarded than one over advanced.

Its not uncommon, particularly on Lucas mags (even when new), to see a difference but I would want it closer than6degrees. First thing to check is are the points gaps both the same? They should be 12thou. Different point gaps will affect the timing. If the points gaps are uneven then something has worn or isn't running true. It's rarely the cam ring that is a problem. Its usually the end housing where the bore for the bearing isnt concentric with the bore for the cam ring, as mentioned above this could be because the bearing insulator is badly fitted. If this is the case a new cam ring wont solve the problem, last resort is to grind back one of the rising edges to get them 180 apart using a dremel. You'll be there forever if you try and do it all with a stone, just use a stone to tidy it up at the end.

If you decide a new cam ring is needed they are available from Dave Lindsley.

Hope this is useful

Andy

The cam ring wont normally wear unevenly, as stated previously the cam ring may be shimmed to compensate. A new cam ring wont change a thing in this case. If in doubt, remove the cam ring & measure the thickness of each ramp, you will find they are ate same. Sometimes the bearing is offset by the paper bearing insulater, sometimes the end casting has mounting holes that are not exactly correct, etc. I have shimmed my cam rings on both manual & auto advance mags with brass shim stock. If you do not have enough clearance for the sim, remove the ring cam & CAREFULLY grind off some material from the OUTSIDE of the cam ring on the side that you want the cam ring to move towards & shim the opposite side. NEVER stone the inside of a cam ring.

This is how I do it & normally like to see both sides within .002 or better.

Would love to hear from other magneto repairers on their process!

Skip Brolund

+1 on what Skip says.

Keep in mind Ian, your issue is probably not with the cam ring, but other items not allowing the cam ring to be concentric with the armature shaft. Keep us posted with your findings!

Skip Brolund