John I don't think you can compare a Norton cam with a BSA. The cable is on the opposite side but it is still tight wire advance because a Norton mag has the opposite rotation to the BSA. Royal Enfield however have a slack wire advance, so with the cable at the front but will still have the same face cam as an M20. Ron

email (option): ronpier@talk21.com

The clockwise Norton cam is marked 'R' There are slots on each side for the A/R lifter...Movement should be the same whether left or right though. Norton went to slack-wire advance after 1948, but they changed the cam drive at the same time and the mag became anti-clock.

I think it might be best to revert this mag to std set up Ron

There were a number of “mods” intended to keep it on the road which are now confusing issues

With std parts - I can help him better long term too

Br
Job

email (option): jonnyob1@googlemail.com

John from the point of view of running, it doesn't matter a jot if you have tight or slack wire advance. But for an anti clock mag you must have an "L" stamped on your cam plate, as seen here on my spare BSA/Triumph and Enfield mags. As per Rik's mag the clockwise mag needs an "R" cam plate.

I guess the Left and Right denotes what side of the plate the points are actually opening on. Ron

email (option): ronpier@talk21.com

Magnetos built from pieces can be a problem, i have come across 3 different cam plate for these mags. First thing i do with an unknown mag is to check the magnetic flux timing. If right is when you turn the mag in its correct direction you can feel the magnetic flux. The points should just break on full advance just after full magnetic flux, dosnt make any differance if its slack wire or tight wire advance for this check as long as you have it on full advance. If you have got this then you are on the way to having a good magneto. But coil and condenser are not checked in this test.