Dave Lemon owner of Mazdatrix discovered a strange phenomenon.
     Apparently a Weber carb on the end of tuned p-port manifold
     can enter a unstable condition where the mixture obviously
     is changing rapidly from way too lean to way too rich.
     The engine goes maximum rough and a ton of fuel air mist
     eight feet high appears over the carb intakes. We are
     not sure what causes this. It could be a mechanical resonant
     condition of the carb intake system shaking the float bowl
     or it could be something to do with rapidly reversing airflow
     confusing the venturi sensor. It happens about the tuned
     RPM or peak torque RPM. One can pass through it. It seems to
     be a function of the jetting. This is a new one on me.
     Paul Lamar

This phenomenon is most likely resultant of the non-tuned exhaust
setting up back pressure.
Blake



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