My Dynon manual said to start with a value of 68,000 and then modify it knowing what the cube says you burned compared to what it took to fill the tanks again. The k factor can be thought of as the number pulses to register one gallon. Ratio the fuel it says you used by the fuel you know you used and either multiply or divide the 68000 number by the ratio. See the Dynon manual for specifics.
I've found the most accurate way to celebrate the fuel flow transducers is to pick some starting point and then plan to not trust it for a few tanks of gas. As noted above, fly enough to burn off about half a tank then refill. Adjust you current K-factor by the ratio of fuel reported by fuel actually burned. After 3 or 4 times, you will be pretty close.
I used 88400 and I fly around 5000 rpm with short flights of one hr. or less with two landings It seems that it burns around 5 gal per hr. Still not quite sure but we all should be about the same. Van's should have some better information along with the settings for the new auto pilot.