ORIGINAL: Jim Thomerson
Model diesel engines differ. I have some which I seldom do any adjusting on. Others are very difficult to start at running compression, so I change the compression to start, and then get it back to about the same place to fly. I'm flying control line with venturi rather than carburator. I seldom make a change on the fuel needle.
My McCoy .09 and OK Cub .049 Diesels are as you described. Both are fixed throttle (control line/free flight) types.
Ed Cregger