Fuel Curves

[Gary Derian]

Those old Lucas FI systems were completely non-low emissions and ran rich at
low speeds.  You may need just a little tweeking to lean out the high vacuum
part of the curve.  Maybe a slightly softer second spring, or a different
angle on the ramp in that range.
Gary Derian <gderian at cybergate.net>




>Hello,
>
>What would an ideal plot of manifold vacuum versus injected fuel
>quantity look like? I am still on the job of tuning my Lucas mechanical
>injection - last night I measured the fuel curve and it seems a bit dodgy
to
>me (although my opinion is not very qualified). At low vac the fuel
>delivery is high, and it drops very rapidly (and linearly) until it reaches
>about one third of its original quantity, and then it changes slope and
>linearly decreases until it gets to max vac. This means that about the
first
>10% of the total vac increase reduces the fuel quantity by about 66%
>and the last 90% of vac reduces it by 33% (the two parts of the graph
>are both linear of course because it relies on springs to derive the
>curve). Does this seem good/bad/otherwise to anybody who knows?
>
>Any comments gratefully recieved.
>
>Regards
>
>Bruce Robertson
>Lucas injected Bond Equipe Sufferer - New Zealand