i tinkered with them once,odds are yours have gone soft and advance too quick?what are your symptoms,,pinging?i use electronic religiously,praise the spark at the right time!you can get away with murder almost with the advance curve on these engines stock,they dont have vacuum advance or anything(if they did it would be great),if it dosent ping but the advance comes up too quick you have no problem,the more advance you can run with no detonation is a plus,even with good springs you can advance till the point of pinging above the factory timing setting for a gain all over.