Triumph 500 650 750 Auto Advance Springs bonneville

This pair of springs are to suit just about all "automatic advance" ignition units fitted to unit British singles, twins and triples of the '60s and '70s.  Original Lucas part number is 54417992.  These springs are tested for tension, and are "heavy duty" , in that they're wound a bit stiffer than the 54412229/54415642 springs that preceded them.  All a/a springs supercede to these.