I like the ability to run lean of peak, so I did the GAMI process, bought 1 injector that was .0005 larger diameter for the hottest cylinder that wouldn’t come into line after methodical swapping and got everything to peak very close to the same fuel flow. After doing this, I asked an IA about the frequency of cleaning the injectors. His response was that the old recommendation was every annual, but after Cessna had some incidents due to crud getting into the injector mounting hole during the annual cleaning, the new recommendation was to monitor EGT’s and if there is an increased EGT noted on one cylinder, clean the injector and see if that helps, otherwise don’t remove the injectors.
Has anyone else seen/heard this advice?
Regarding differing sizes of injector opening: I’m not sure the variation of when the cylinders reach peak EGT is due to variations in injector hole size or simply variations in MANY things in the cylinder having the cumulative effect of different fuel/air flows and capacities. The solution is to vary the injector nozzle size, but it is not necessarily the cause. At least that is my understanding...
To the original question: I too would never change the position of the injectors because 1: I went to a lot of trouble to get them to peak within .1 gph of each other and 2: I have a known system with known characteristics and randomly changing the injectors will render that hard gained knowledge pointless. When something in the engine changes, I’ll know it and I’ll know that changing the position of the injectors didn’t cause it.
