In my experience there is no difference in performance between the competition mags and the standard ones. I have tested the resistance on most coils coming through the workshop, just out of habit really as they all have to be rewound anyway. The resistance on all satisfactory coils is between 4500 and 5500 ohms. I have even counted the turns on some coils and there is a variation between about 7500 and 10000 turns but no correlation with either type of mag. I suspect the number of turns was dictated by the physical size of the coil. The more experienced coil winders, usually women in the Lucas factory, would be able to do a really neat job and get lots of turns on before the coil became max size. The less experienced staff might have had problems wrinkling the interleaving paper or snapping wire and creating soldered joints which causes air gaps and takes up space. I have no problem getting 10000 turns on a coil but 9000 is plenty to achieve the performance required. I don't believe the girls in the Lucas factory snapped the wires that often because it's a real PITA joing the wire again and very time consuming so a fail to be avoided! The trick is to use a good quality tensioner and not run the machine too quickly so you can see any potential snags as the wire comes off the spool. I can wind about three in a day from start to finish which includes stripping the old coil down. Some Triumphs (excuse me whilst I spit!) used mags which, at first glance, look like a K2FC; i.e they have screw-on pickups and the cam housing is attached with 1/4 whit hex head wire lock bolts, but these mags have a breather hole in the underside of the body which a genuine K2FC does not have. Also the Triumph mags often have the standard screw-on points cover. Some of the racing mags had a one-piece, stainless steel taper/capacitor housing (part of the armature) so that the drive shaft wouldn't separate from the capacitor housing (the bit the earth brush rubs on). The performance of the mag is mainly due to the construction of the armature and capacitor. Capacitor technology has moved on so much that there are a few capacitors which do the job really well, both ceramic and paper film dielectric epoxy insulated, all of which the mag restoring fraternity use widely depending upon application. Lucas used two types of capacitor in their K2F armatures, square cans and barrel type but both will fail over time due to the construction and materials available in those days. Surprisingly some mags are still working fine with capacitors which are 50+ years old. Going back to the original question, a K2FC will have a body without breather hole, a screw cap points cover with breather pipe, screw-on pickups, and a cam housing attached by 3 x 1/4 whit screws with wire lock holes but there will be no difference in performance between a K2FC and a good K2F........... in my opinion!
