BTH Magneto Direction

I have a BTH type M1 - B2 Magneto that I want to fit to my Ruston APR. This
type of magneto was originally fitted to the engine but the one I have
sparks when spun in an anticlockwise direction whereas the engine needs one
that sparks when spun clockwise.
Is it possible to convert the one I have to operate in a clockwise
direction? If so how can this be done?
Liam Hoskin
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A change of cam ring should be all that's needed. Talk to Mike Green at Independant Ignition if your pockets are deep, otherwise scour the sales for an otherwise knackered clockwise mag.
Reply to
Nick H
IIRC the B2 was a special for RH but similar to the B1. Even within nominally the same model BTH do vary. I'm fairly sure you'd get away with simply switching the points carrier from a LH to a RH which is necessary in any case. (My memory is sketchy but its possible the B2 has the cam-carrier separate from the end housing and the whole ring/carrier can be flipped) I've never yet found an M1 where the cam ring wasn't corroded immovably in its housing. If it will move and the points carrier switch doesn't work on its own: then extract the cam ring and flip it front to back so the profile works in the right sense, then position it so that it opens the points a smidgeon after the strongest magnetic pull. Grind a new dimple for the cam lock or pin and that should do it. hth (and E&OE :-)
Reply to
Roland Craven

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