I have ran a couple of JD 3300's many years ago. Generally the book settings are for perfect operating conditions where the crop is dry and are also for maximum capacity. We normally had to run the chaffer somewhat closer and the seive slightly closer than the book to keep the trash our of the bin. This reduces maximum capacity a little but will give a cleaner sample. We also usually had to run the cylinder closer and faster than the book as there are always some green patches or heads in oats. Like I said, if everything is very dry and threshing and cleaning easy the factory settings are probably fine. 3300's were a good little combine, less problematic in my opinion than the 4400's. Sems like my brother had a lot more problems with his 4400 than his or Dad's 3300's.

John