Timing and Metering Valves

[TerryB]

I started my working career working on Big Cam Cummins along with a few Small Cam engines, learned and done everything on these engines. About the time engines started becoming more electronic controlled, my path sort of veered away from Cummins and more to International, Detroit and Cat. So I didn't really get to know the electronics of a Cummins engine. Now, as the owner of a CM570 I'm trying to learn the electronics. One area is the timing and metering valves and how they do what they do. The timing valves, how do they control timing? My thoughts: The injectors are mechanically controlled, the camshaft is timed to the crankshaft. How can the actuators affect timing?(this is when I try to compare this engine to a Big Cam engine and it's timing. I know, can't do that). I'm thinking the timing actuator controls the exact time the fuel is fed to the injector, depending on the position the injector is at that split second, determines the timing. The injector could be already half way to being bottomed out before fuel is supplied to that injector, or maybe almost bottomed out if the timing is more retarded. Would that be correct? I'm not asking what position the injector rocker would be at any particular time, I'm asking if that's how timing is controlled? On the metering valve, this seems to be a little easier to understand. More fuel=more power. The metering valve controls the quantity of fuel supplied to the injector. How is this achieved? As far as I understand, the metering valve does not control fuel pressure going to the injector.(I could be wrong on that) Is the metering of fuel controlled by the length of time the metering valve is held open? The longer the valve is open, the more fuel goes to a particular injector. Sorry of being long winded, just trying to get a better understanding of how this engine operates.