Friday 4 June 2010

C.A.V magnetos

This is the C.A.V magneto that was fitted to my 1927 flat tank Norton. Produced by CA Vandervell & Co Ltd. they were fitted to many vintage Nortons. The CAV has a strange reputation; some would not touch them with a stick while others have used them for years without any trouble.

The issue is the little fibric wheel that opens the points. It looks a bit flimsy and one can imagine that when it wears unevenly the points gap may vary constantly which is not a good idea for a magneto. For the rest though, it looks very well made and it sparks beautifully. Does anyone have any comments on this?

Martin: "Interesting views on old magnetos... For what its worth my own experience of early magnetos has been surprisingly good, as the early makers didn't know about how to make acceptable electrics cheaply, so the earlier mags are generally very well made and work well. The early Bosch mags are wonderful, particularly the DA2 open magnet design found on pre 1912 veteran Triumphs. This was replaced by the enclosed magnet ZE1, which is lighter and more waterproof but not as good in the sparks dept.

Another German manufacturer, Ruthardt, developed a compact design of mag in about 1910, and this was copied by CAV in the UK and is an excellent device. Early Rudges used Ruthardts with a long splined shaft so they are easy to spot in an autojumble, as they fit nothing else. 

The secret to all mags is having them in good condition, particularly windings with good insulation and a good capacitor. Good bearings too of course and a strong magnet help to keep a good spark. However magneto rebuilding is an art which does not come cheap and not all rebuilders offer comparable service, so you can spend a lot of money and still have a poor mag... Unfortunately there are some unscrupulous people in this business, but word soon gets around and you can avoid using them if you ask advice about who does good work from fellow enthusiasts. If your CAV is well rebuilt, I would have no hesitation using it."