Eddy 1405 tuning advice

Totally unscientific, but factory Carter springs are probably on the stiffer side (depending on the engine). I don't know for sure, but I'd guess they were closer to the 8" springs in the Eddy kit. I'm sure, however, that every engine had a specific spring. I don't think you'll feel a difference between a 7" and an 8" spring. You have to be pretty far into the pedal to get into the power circuit most of the time. Have you checked cruise vacuum on your combination? Even if you're idling at 14", your cruise vacuum may be higher than that.