As far as setting the fuel racks, it is a delicate procedure that has stymied many a first timer. Getting it "by the book" is, in my opinion, pretty much impossible the first time around. It will drive you absolutely mad. It took me quite a while to develop my technique and I'm sure I'd have trouble today since I've been working on electronic engines for so long and haven't seen a mechanical governor in years. You will have to settle for "close enough" unless you have that magic touch or weeks to fart around getting it perfect.
I will say that the closer you get the set up to the description in the book, the better the engine will run but most people can't tell a crappy tune up from a good one by listening to the engine.
Are you working with a book or any previous knowledge of how to go about the adjustments? I can walk you through it but we would need to get some terminology straight so that the communication is good.
Here's a concept for you. Try to get your head around this and tuning the engine will make more sense. At least it did for me.
OK, here goes:
These engines always want to run at idle. That's right, idle. If you were to start the engine with the valve covers off (something I used to do all the time using special cut away covers) so that you can observe the injector fuel racks, you would see that, with the engine stopped, when you placed the engine stop lever on the governor to the run position and the throttle control lever is at O% throttle (idle) the fuel racks will go immediately to "full fuel" or, all the way in. Then, when you crank the engine and it fires, the racks will immediately return to "idle" or move outward. That makes sense, right?
But, with the engine running, when you move the throttle lever to say, oh, 50% throttle, you would see the fuel racks move inward toward the full fuel position and then as the engine speeds up, they will move back out toward idle and pretty much stay there until the throttle setting OR THE LOAD is changed.
I emphasize THE LOAD because that's what these engines are all about. The only time the fuel control racks will stay all the way in for more than a second or two is if the engine is at full throttle and is FULLY LOADED. Under any other conditions, the racks will stay back toward the idle setting.
It's because the governor is always pushing on the racks to go to full fuel. The high speed spring exerts exerts that force. But, the governor weights, because they are spinning, overcome the spring pressure and return the racks to idle any time the engine is not FULLY LOADED. You can be running down the bay at 2200rpm but if you could see the fuel racks, they would be hovering closer to idle than to full fuel.
So, it can be said that:
The engine only adds fuel to increase rpm and overcome a load. But, when that rpm is reached and the load is being "moved", the rack returns to idle to MAINTAIN that rpm and KEEP the load moving. Nothing more. That's what it's all about. Adding just enough fuel to overcome the load and gain rpm but then backing off on the fuel and then just MAINTAINING that setting.
That's why it is so important to get all the cylinders doing their share of the work by having all the valves and injectors doing exactly the same thing so that they are "balanced".
Yes, the fuel rack adjustments are made in the full fuel position but getting them dead nuts even helps the engine idle better. This eliminates the governor weights from spinning unevenly, moving in and then out and "hunting" against the high speed spring due to a power imbalance between the cylinders.
I hope this helps and doesn't confuse you even more.