Quote:
Originally Posted by v8volvo
Well said, agreed. 
Yes exactly right, the smoke screw gets removed (or at least screwed a long ways out) in order to disassemble the top of the IP/throttle control system. So they would have had to do this during the service that was performed, and then they would have had to get it reinstalled to the same setting it had been.
Normally the way to do this, if one is working on the IP still installed on engine using "seat of the pants" methods, is to very carefully note the position angle of the smoke screw before disassembly, and then count the number of turns required to remove it from the pump upper section housing. Then one tries to reinstall it in exactly the same position and with the same number of turns, so as to have the system work as it did before.
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There's a much easier way to do this. There is (or should be) a collar crimped onto the fuel limiter screw ("smoke screw" in your terms). And there is a lock nut not far from that collar. Usually there is about one turn (often less) between the collar and the lock nut. Normally, I simply loosen the lock nut, then remove the limiter screw. Later, just install the limiter screw back in the same position. But, if you want to be more precise, you can count the number of turns (or "flats") between the collar and the lock nut.
Tom Bryant