The sites listed above sound like excellent sources for the information to tailor your own advance curve. Speaking on the change of the springs and weight of the advance weights, yes these could have the same or equalizing effect if not done properly. lightening the weights with the addtion of a weaker spring could put you back in the same spot. The shape of the weight were it touches the advance cam will change how much the Dist can advance. Also the size of the pin on the bottom of the advance cam and the slot it fits into will control the amount of advance it can reach when the advance weights sling out.Both the rate and the amount of advance must be considered when tailoring a "Curve".This should be done off the car in a distributor machine for best result so a person can monitor the changes in relation to the distributor RPM.Distbibutor RPM is half the RPM of the motor, so 1 degree added to the centrifugal advance is actually 2 degrees when operating in the motor.Paul
