I am trying to research the auto advance specification for the Low Compression engine using an auto advance distributor.
By examining several Austin Seven distributors I have found that there are two variations in use on the Ruby series of cars,
a 3 degree limit to the auto advance
an 8 degree limit to the auto advance.
The limit of the auto advance, the bob-weights under the plate holding the contact breaker assembly, is achieved by the size of the hole in the bob-weight support plate. These plates are marked with the number of degrees the system is set to. I have also found the odd one or two plates marked 10 degrees and even 22 degrees but I think these must have come from other vehicles.
My quest to to find out whether the low compression engine in the Mark 1 Ruby had a three degree auto advance and the high compression engine in the Mark 2 Ruby had the 8 degree auto advance.
If anyone has any technical information which reveals the correct advance range please email me at mwatts@sle.uku.co.uk I would also welcome information from Ruby ( and Pearls and Opals ) owners as to the date on their distributor ( see the plate on the side ) and the number of degrees marked on the plate supporting the bob-weights
With thanks Malcolm Watts