AC air champ seed plates

ANY air planter prefers ROUND seeds not flats. So, right off the bat you aren't right. Thee most common corn seed plates used on AC and DA air planters was the MEDIUM disc or SMALL MEDIUM size disc and the customer used medium round seed. I've never used LARGE or SMALL discs. Without seeing your seed laid in your seed disc pockets it is hard to say, but I feel it won't work well. Probably have many skips.

I'd say to take a look at the seed before you jump to conclusions. I hope that you can make it work. Darrel

The issue with flats is it takes more air pressure to hold them in - at least 2 WC".  The air system is very forgiving IF you have the pressure.  Tricks like a hot alternator putting out 14 V and pulling off that as on is supposed to - make sure the voltage is the SAME at the motor as it is at the source. Bad switched, connectors etc will drop volts when the amp draw goes up. We found grounding the negative wire by stripping it back and adding a wire ground from there to the motor base will increase motor speed. Make sure the squirrel cage blades are cleans and turning in the correct rotation.   I found an air system off a White planter worked great- they are adjustable. I installed the short cut off pads and tickler brushes off a White (same as the milo kit on the 385) added a tad more air pressure to eliminate skips and the ticklers wiped off the doubles.