> The Lucas PI is only regulated by air flow, by using manifold depression,
> there is no adjustment to the delivery for engine speed, yes the metering
> unit turns faster as the engine turns faster but with the exception of
> losses of delivery caused by flow rate characteristics through a hole in a
> given time, the time reducing a rotational speed increases, there is no
> change in fuel delivery for a given vacuum as a result of speed increases.
Graham, I'm almost certain that the fuel flow remains relatively constant
*per firing* as determined by the displacement of the metering pump.
Otherwise, there would be a huge variation in mixture (from too rich to run
to too lean to run) from, for example, 2000 rpm & 10" vacuum to 4000 rpm &
10" vacuum. Since there would be roughly a two-fold difference in air flow
between those two conditions, there *has* to be a corresponding difference
in fuel flow or the engine will not run.