THERMOQUAD QUESTION

Hi Folks

Can anyone tell me the purpose of the small spring that is in the area of where the choke pull off attaches. It looks like an advance spring from a distributor. Newer models have a spring that wraps around the shaft instead.

I have a couple of these carbs, and they all have different strength springs on them. Figuring if I knew the purpose of the spring, I could figure out how strong it has to be. Picture copied from a FABO post. Thanks