Originally Posted by 1957willyman
if i need to change springs in distributor do i need to go a stronger spring? do i need to change bushing and weights to? or do i need to limit travel of weights
The bushings are the things that control how much mechanical advance there is. The stock bushings only go to 18 degrees- if you need less mechanical advance- which you will- you need to either make or buy bushings that will limit the mechanical advance more, or use some other method to control how much mechanical advance the distributor supplies.
The stiffer spring will keep the advance from starting so early, but you still need to get control of your idle before getting into the mechanical advance.
You can use a vacuum advance, no problem. Connect it to a ported vacuum source and limit the amount of vacuum advance to about 10 degrees.