Thank you, I will look at the diagram of the pump to try and understand what you mean. If I understand correctly what you write you are referring to pre-ignition, which is a special type of knocking noise and if left uncorrected will lead to piston crown burning because the temperature of the flame is too high. This is especially bad for 1970's petrol engines.
The noise from my high pressure pump (injection pump) is almost exactly the same as a hammer on an avil that is used to make horse shoes and in time with the firing of the cylinders. A similar noise can be heard as water hammer in water pipes when air gets into the system. Unfortunately just a few weeks ago I knew nothing about diesel fuel injection pumps, so I really don't want to strip one down at this time and possibly do more damage leaving myself without transport.
I am going to turn the screws a bit more tomorrow until I can make the engine smoke going up hill. At least then I will know it is getting enough fuel.
Terry