[Rick Parker]

Chopper is dead on. The bushing only limits the "total amount of timing" in this case (28) degreees) that the distributor will add to an any inital setting. IE:Before the centrifical advance begins to feed in more timing. The small diameter wire silver springs being the weakest, have very little control over the flyweights, and allow movement of the flyweights to begin at about 800 engine RPM. If the initial idle is too high (above 1000 rpm) it will have already begun to advance the initial setting at a very fast rate. View your max advance with the timing light, at about 2800-3000 then see where the initial timing falls while at idle. If it is idling at about 1000-1100 and you want the initial to be less, (assuming the cam, and inlet stem will allow it) you will need to go to a stiffer set of springs and a different bushing. Don't over do it, the weaker the springs the more irratic the timing will be at low RPMs and the timing will "Hunt" causing your idle RPM to rise and lower for no apparent reason. If you can lower the idle by adjusting the idle speed screw on the carb you will then begin to "Back out" some of the "mechanical timing" the weaker springs have allowed and you will see the initial reduced timing visable with the light at idle.

Clear as mud?