Misc: Ignition ATD Springs

LoneStar

LoneStar

Well Known and Active Forum User
VOC Member
Hello all,

I've invested in a set of new ATD springs (PR22A/D, Lucas 498157/S). They're claimed to be NOS Lucas, but arrived without the original packaging - so I have some concern as to whether they're correct. These are identical to each other; I believe some designs use two different springs in a set, providing a more complex advance curve.

Does anyone know if these springs should be identical, or different from each other?

Thanks,
 
C

chankly bore

Well Known and Active Forum User
Non-VOC Member
As far as I can remember both springs should be identical. Lucas did supply slightly heavier springs for machines with sidecars. Not sure they were ever specified by the Vincent factory. The Brightspark Magneto site has further information on this, including a PDF of the original Parts List and a diagram of the advance curve. Your part no. is correct.
 
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