Larry,
   I'm playing with my own design ideas ( slide carb) and one of the
   variables
   is an adjustable ( in height via screw thread) needle to lean and
   richen the
   mixture and the other problem of different seat jets sizes, I feel
   could be
   solved with a variable pressure fuel pump ( from 1.5 psi +). This
   could be
   managed with an idle jet under the jet/seat.

   I envisage the variable pressure pump an idle screw as the course
   adjustment, with the needle ( into seat/jet) as the fine adjustment.
   What do you think.
   George ( down under)



   George,
   The best way to manually control the fuel flow is a barrel valve type
   system. Needle valve systems are known to have problems with thermal
   growth
   of the components changing the mixture as well as being very prone to
   contamination errors.

   The easiest way to vary the fuel pressure is to pulse width modulate the
   supply voltage to the pump. I do have an easy way to do this, I just
   have to
   get my software/electronis friend to change the control signal from
   temperature to pressure. My friend makes a dual fan controller for
   automotive use that pulse width modulates the fans based on engine
   temperature. I had him design this for hot rod stuff years ago.
   Works very
   nice. The design could be changed to control a fuel pump. We could
   drive the
   pump based on a combined signal of throttle position, manifold
   pressure and
   rpm. One advantage is now the fuel pump only uses the electric power
   required to obtain the required pressure. Now leaning can be done with a
   trim pot on the panel changing the overall trim of the system.
   You can check out the original I-FAN2 at
   http://www.hms-electronics.com/fan/index.htm
   <parse.pl?redirect=http%3A%2F%2Fwww.hms-electronics.com%2Ffan%2Findex.htm>

   Let me know it this is something we want to pursue, I and will talk
   to Dick
   about what it will take to make one for our purpose. This may
   actually be
   the easiest way to make the low cost injection work.
   Larry


   Why not use a mechanical pump like everyone else using mechanical
   injection?  Yes, you CAN drive them with belts.

Tom


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