Well, logically, if an injector is safely within the range,(lbs/hr) of the fuel requirements of the engine and the Engine management systems are working properly, you can understand that the primary reason to be running rich is leakage.
The single pintle design is the least likely to clog and keep the valve from closing, but by the same token, may run a little wetter at low volume.
Lucas has reduced that by using a tri-cone channel inside causing enhanced vaporization, IMO.
I opted for the four-hole disc type mainly out of curiosity - they work well, but I know my lucas were leaking as evidence of loss of fuel rail within 20 mins. of shutdown.
The fords (although any good ones) still hold after several hours.
luck,greg
