Whilst I cannot state with 100% certainty this is the case - it is what I believe to be the correct assumption and what I have been advised on previously
No Chris! They are both tight wire. The M20 mag is driven anti clockwise, the Norton mag is driven clockwise. To my knowledge it was only Royal Enfield who adopted the more sensible slack wire advance. Ron
As for the Norton. The pick up and adv/ret cable are on the left (nearest the barrel) But as I said, is still tight wire advance. :slightly_smiling_face: Ron
I am sure that you know, but thought I would mention it just in case.
Some WM20s out there may have an incorrect post war mag fitted (mine has). My adv/ret wire exits opposite to the wartime mag and is a slack wire advance.
One of the reasons that Norton mags are so hard to find is that they are snapped up by BSA owners in order to use the points end for converting to slack wire advance. The A/R cable is not heavily loaded though and it seems logical to me that choke and ignition both pull back for normal running.
Norton bodies, incidentally (and this has nothing to do with direction of rotation) have the HT pickup next to the cylinder. It is a real fiddle on the 16H and may not be possible on some other engines.
The only help I can give you is that for my mag, which is a slack wire advance and not the correct set up for a wartime mag, the cable to advance or retard the ignition is on the left running parallel to and nearest to the barrel when viewed at the points end of the mag.
The HT lead or wire which runs from the spark plug to the mag pick up is farthest away from the barrel and close to the oil pipes at the oil tank.
My conclusion from this, rightly or wrongly, is that no matter which mag you have (tight wire or slack wire advance), the position of the HT pick up is the same.
I guess it would be fairly difficult to remove the pick up if it was on the other side i.e. very close to the barrel.
Hans has a picture in the Technical Section of a slack wire advance mag which shows the position of the adv/ret cable. Unfortunately, it doesn't show the position of the mag pick up and HT lead.
I haven't got another M20 mag to do any comparisons with, so please ignore all of this if I am talking bo&*ocks.
"... Hans has a picture in the Technical Section of a slack wire advance mag which shows the position of the adv/ret cable. Unfortunately, it doesn't show the position of the mag pick up and HT lead...."