Thread Rating:
  • 0 Votes - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
SU Oddity?
It's a good question. Sometimes one can find that a particularly heavy oil in the dashpot, which makes the piston slow to rise, means that the restricted choke increases the airspeed over the jet and briefly richens the mixture, the opposite of what one might expect.
If perchance your piston is undamped and could rise very quickly with the cornering forces (which I doubt) you might stall the airflow briefly and so weaken the mixture. Just playing devil's advocate. Since this is something of an academic discussion, why not?

More to the point, I do wonder if you are experiencing a fuel surge effect. If the fuel climbs up the float chamber wall and permits the float to drop you might get an overfull float bowl briefly as the needle valve is fooled, especially if the fuel pressure is high. The exact problem Miss Shilling's restrictor  mitigated, under much more arduous conditions of course.

What pump are you using? An SU or mechanical pump should be ok. An unrestricted Facet could be a problem.


Edited to add, Dave beat me to the first bit!
I am using an SU Low Pressure pump, so I would expect that to be fine, I have never had reason to suspect it in many years.
There is definitely damping from the light 3 in 1 oil, actually a surprising amount considering how thin it is.
It is definitely getting richer, not weaker, on cornering.
There is a lot of food for thought here with all these ideas!
(15-02-2020, 08:40 AM)Steve kay Wrote: Evidently still side effects from Cupid's arrows fired off at lusty humans on St Valentines Day. Wouldn't want to be at sea on a sailing vessel today, so a three cylinder compound would be preferable. Nor sure that any of us Seven sailors have experience beyond reciprocating machinery, thuogh our worthy historians may come up with a turbine powered Austin, if Solihull can manage it then surely Longbridge can.

Been out in in worse than today, Steve.  I always took the view that the boat could stand it longer than you could.  A bit like Austin Sevens, really.
Alan Fairless
I made a point of watching Master and Commander the other day, whilst the storm raged outside. Was great!


Forum Jump:

Users browsing this thread: 1 Guest(s)