USE THIS AT YOUR OWN RISK
The link below will bring you to google drive, then from there you need to click the download arrow to get the excel file.
To make it simple, only change the data in blue. the arm value in yellow is calculated from the scale weights, but you can simply type in a new arm value. NOTE: the arms in this are based on a datum of 50 inches. Most RV4s seem to have used 60 inches, but the plane I made this for used 50. This is a fairly all inclusive spreadsheet that you can start with the scale measurements, enter oil quarts, change the remaining fuel after flight, change the cg chart envelope, etc.
https://drive.google.com/file/d/0Bx3YpAZ5ckLIaTNuVmk2dTFRY0hEdU91V21aUzlPdXhwLXdr/view?usp=sharing