1948 ES2 advance/retard

Hello everyone.

i have just enjoined the club as I am in the middle of trying to restore my fathers Norton ES2 1948. I am currently having the magneto restored. We have also have the head reseated and new valve guides fitted to take unleaded. But I have come a cross a problem which I an unable to workout and that is setting the advance and retard setting is there anyone who could take through this step by step?

i would be very grateful

Jonathan