help with tuning an AED 750 Ho

I have the initial timing set at 17-18* with an 18* bushing in so it's 36 all in.. Sorry, what is the IFR? is that the idle feed restriction? and where is that at? sorry "novice" I have been trying to educate myself as much as I can.... Which springs did you say? 1 of the medium "blue" and 1 of the "light" silver? Thanks a lot.