Timing magneto

[chrismoss]

Hello. I am a cabinet maker and therefore useless with anything metal or vaguely metallic!!
Have a '27 chummy, had the mag rebuilt, only book I have is 1933. How do I time it????
The car is in Frome, Somerset, if there is anyone local who is willing, I'll pay, honest! Otherwise, can somebody perhaps mail instructions? Thankyou.
Chris