this is the hydrolic head of the pump
and this is the camplate. At the right, there is a 1.6Td camplate et the left is an early 1.9Td camplate (thanks tp X@v for the pictures)
So the "rod" in the middle of the hydrolic head is turning AND back and foward in the hydrolic head. The fuel is skeezed in the head and then distributed in the good cylinder at the best moment.
1)Now, the 1.9TD camplate has more lift... it will skeeze the fuel farther.
but.....
2)THere is also a sleve OVER the "rod" which is covering holes. When the holes are covered by the sleeve.. the fuel is stock in the head of the pump and thus the only exit of the fuel is the injectors.
When the camplate push the "rod" at a certain position in the head, the sleeve (which is
fixed by your right foot
uncover the hole. At this time, the fuel can get out of the head by this hole and the injection then stops.
When you push your right foot farther, it takes more time for the sleeve(which is now farther) to uncover the hole and the injection last longer.. you then go faster.
So a camplate with more lift has the possibility to inject more fuel than a camplate with less lift. For it, you need to be able to adjust the maximum position of the sleeve. This can be done easily by turning the well know fuel screw.
Another thing to consider(which will not be important here) is the RPM range, a camplate with greater lift will travel much more thus being accelerated much more also. At a certain point, the camplate may not have time to comme back to it's rest position and you may have problem to go above 5000RPM.(stronger spring can be used)
3)Now the timing of the injection is also important because we want to have the most efficient combustion possible. Two things must then be considered
a) We want the greatest part possible of fuel to be burned in the position of the cylinder where the greatest torque is produce. i.e. where the lever arm created by the piston, rod, and crank pin is an angle around 90°.
b)we also want all the fuel to be burned... and the maximum pressure is created at TDC.. so we must inject in advance the fuel, not to much because we want it to be burned has mentioned in a) but enough to burn completly
.....if I explained well enough, you should now understand that a timing of 1mm, may not always be the same
effective timing INSIDE the engine.
now... the question was to know if the lift of the camplate could change the effective timing enough to change the efficacity of two engine with the same pump timing!!!!!!!
the thing is... when a cam has more lift, his slope is greater (because the distance between injection must stay the same).
For example.....at 1mm of lift, the pump with the smallest lift inject fuel later (effective timing retarded) and the pump with the greatest lift inject fuel sooner because the slope is more abrupt.
So... want is the best setup according to a certain timing....??!?!?! this is want I want to know