Must be talking different springs. Most of the light springs I've messed with are full in around 1200rpm. So when you set the timing at say 23* at 900 idling in neutral then drop it in gear it takes timing away making it want to stall, at the timing is all over the place.I guess if your idling at or near 1200 in this case it would be a wash. So you are saying with light springs installed you have no curve? From 600 all the way up?
all the light race springs i've ever used will bring the full centrifugal in at 1100-1200rpm using a 9 degree plate. so if you set the total centrifugal at 36 degrees there will be 36 degrees at 1100-1200rpm. naturally below that rpm advance will reduce. there is a point were the springs can be too light and not let the weights fully retard when the engine is shut off but that would only happen if someone tries to use only one of the race springs. i've found erratic timing to be other issues than springs.
