The POSA, Lake Injector, RevFlow and AeroCarb are of all the same jenere. The operate under minimal fuel pressure, ie gravity feed in 99.999% in most cases. The POSA was originally used on motorcycles. The fuel pressure was about .2 of 1 psi or less. If memory serves, 1 psi of fuel pressure requies about 40 some odd inches of vertical height. Fuel is 6 lb per gallon vs water being 8 lb per gallon. Water requires about 27 inches of vertical height for 1 psi. The above carbs all operate the same. Fuel arrives at the carb needle either directly in a non adjustable mixture option or through a fuel control valve at the carb that leans the carb out. So if you have 12 inches of fuel pressure with a full tank and 3 inchs at a quarter tank, your fuel pressure is reduced accordingly.This usually makes an engine run lean if the carb's fuel adjustment is set up with a full tank of fuel. The above carbs do not have a float or diaphragm. The do not have an elmulison tube to pre mix air with the fuel to break the fuel up into droplets prior to being injected into the intake. Thus the term "dribblers". If you have a mixture control, you set the carb up so you can actually add more fuel to the engine. This requires that the mixture control when set initally be pulled out a little so you can go "over rich" if necessary. If you do a 3G pull up, you put 3 times the fuel pressure to the carb and you can make the enigne stumble. If you go over the top, a 2G "push over" you can make the engine run lean "stumble" and almost quit! Plug the fuel vent with the "Jesus Bug" and the engine will quit in short order. The Ellison uses a diaphragm in the fuel well. This is actuated by a teeter todder on the main fuel valve. Fuel pressure via a fuel pump keeps the pressure constant to the carb irrespective of the amount of fuel in the tank so the mixture is constant. The fuel jet has about 100 (just a guess) .006" or so holes in it so the fuel is broken up into particles vs drops as it is injected into the intake manifold. The mixture is adjusted by rotating the main fuel jet relative to the airflow, vs. restricting the flow of fuel as on a POSA, Lake, RevFlow or Aero Carb. The Ellison EFS-2 is no longer in production due to lack of sales when the AeroCarb came out. The EFS-3 is a little big for the VW but can work by restricting the throttle position. The Rotex Carb is not an Ellsion. It looks similar, but look at the details to get the full picture.
Steve Bennett Great Plains Aircraft ifly...@msn.com
