The wing LEADING edge is 70 inch aft of datum as shown in Section 7 of builder manual. Measure from there. 80 inches sounds too far aft just looking at the sketch in builder manual, but measuring from leading edge of wing should be easy with a level and tape measure. Make sure plane is level.Recalculating weight and balance after changing some avionics, need to know what the ARM is for the panel. Not at the plane so can't measure. By diagram appears it is roughly 80 inches aft of datum, but wondering if anyone knows the exact number.