Ken Welter has been flying a Weber for a few years on his Coot. I
         think he
         is tricking the float chamber by using dynamic air pressure to
   lower the
         fuel level.


     The Weber uses a accelerator pump jet. The carb will pull through
   that
     jet at low altitudes & WOT. Similar to the Holley power-valve. At high
     alts. there wouldn't be vacuum enough to draw through that jet. Mild
     automatic leaning. The Weber is a complicated device. It won't be
   easy
     to duplicate, even just one circuit. My bet would be that when
   finished
     the duplicate would cost twice as much as the original. You can't make
     10 parts and get any economies of scale. There are at least 10
   tunable
     circuits on a Weber. They wouldn't make the carb that complicated if
     they could do it simpler. I think it would be folly to go into the
   task
     of making a carb. Buying a available unit is a vastly safer course. I
     understand why everyone would like to make a custom unit. It may
   work, I
     just don't think it would be cost effective. As much as everyone
   has had
     some difficulties getting started I really believe Tracy's unit or
     another EFI will end up being the easiest in the long run. If not that
     buy a standard carb, and adapt a electronic ignition. My $.02 worth.
     Bill Jepson


     Bill there is a world of difference in the operation of  a car and
     an airplane engine. I am not trying to duplicate a Weber.

     I'll be happy with the mixture anywhere in the range of 10:1 to 20:1.
     The AC engine runs at constant RPM and load for 99% of the time.
     The pilot sets the mixture as needed.

     Klaus ran his engine with a small hole into the intake manifold
   connected
     to a gravity feed tank. No venturi. No other parts. Nada. Nothing.

     Klaus has also tried EFI. He took it off. He gets 50 MPG at 180 MPH
     with a carb. He went 254 MPH in the Dayton to OSH 500 mile race with
     a carb.

     Many people have had trouble with EFI. Its not worth it. 99% of
   the airplanes
     out there have trouble free carbs and every mechanic knows how to
   work
     on them.

     Paul Lamar ...No rotor no motor.

   Hi Paul,

   FWIW, I support Bill' s sentiment.

   A right and proper carb is a complex animal and will be extremely
   difficult to develop. By your own words, you state you'd be happy
   with a
   mixture from 10 to 1 to 20 to 1----- the rotary already suffers poor
   fuel economy, but at this time it's tolerable, what will 10 to 1 do to
   the BSFC ? Will that still be tolerable?

   As for the 99 % of the time, that other 1 % is called a go-around and
   that is not the time to have a carb decide to stop your engine.

   Your talents and vision are much appreciated, but in his instance you
   are trying to reinvent the wheel to save a couple bucks. If the
   difference of a couple hundred dollars between a "new" carb and an
   existing proven / slightly modified carb is a purse breaker, then
   perhaps that person should rethink his/her hobby options.

   I believe you were on the right track developing the turbocompound. This
   technology does not exist in present day hardware and will take a
   proven
   engine to a new level of performance and economy. Consider this: if you
   knock heads with Larry and develop a turbocompound that will increase
   rotary efficiency 15 % what do get in return?  At 12 GPH and $3.50per
   gal, 100 hours of flying costs $4200-------15 % off that is $630. That
   equals one carb. After the second hundred hours, the other carb is paid
   for. After the third hundred hours, you need to take your wife
   somewhere
   nice! The real benefit here is the turbocompound will keep giving back
   in economy whereas the lower cost carb only saves you money once, at the
   time of purchase.

   I'm not pro carb or pro EFI, I just think as a group we can use your
   brain to better advantage and would like to hear opinions of
   others.                Thanx, Dave M

   The fuel burn is a function of the mixture. The pilot sets the
   mixture and
   leans the engine at cruise and it stays there for the majority of
   the flight.
   This is the major factor on fuel burn. Other things like atomization
   of the fuel has minor effects at high engine power.
   This could be done with a petcock and gravity feed. Nothing else is
   needed
   in cruise mode. This is exactly what the Wright Brothers did.

   Aircraft carbs do not have accelerator pumps.
   Because of this your instructor told you set the mixture full rich
   in the pattern.
   He also told you not to move the throttle lever rapidly.

   One of our problems is there are no side draft aircraft carbs available
   for aircraft engines as far as I can find out. The rotary is a side
   draft engine.

   Paul Lamar



Many (most, all?) aircraft carbs have accelerator pumps..    The three
different carbs I have played with all do, anyway.  The flying club I
was a member at had us use the accelerator pump as a means to prime the
engine on all of the Lycoming non-FI engines.  I use a combination of
priming and throttle pumping (3 shots of primer and 1 pump on the
throttle, when cold) on my 182 - gets fuel to the cylinders (primer),
and the complete intake log (throttle).  My Varieze doesn't have a
primer, so pumping the throttle is the only way..  Marvel Schebler MA4-5
on the 182 and MA3-SPA on the 150 and Varieze.


Matt-

I stand corrected.