Bill:

In response to your last post, I went back to read some old threads discussing pumps and the Cline regulator. Let's see if I've got this right (whether or not I understand how a Cline regulator avoids delivering fuel to the carb without higher pressure than a line, without the regulator, to a tank that has no pressure other than air pressure). For simplicity, let's say that a line from a tank with an open vent line is "normal" pressure. (I presume it has something to do with air pressure). (I know nothing about the intricacies of the YS system and my comments below do not attempt to include that):

1. The Cline regulates, in the "true" sense of the word, so fuel is delivered to the carb at "normal" pressure. The pressure in the tank is there to ensure reliable fuel flow to the regulator only. (I saw some heated debate about this on another thread, but your last post seems to agree).

2. Pumps may or may not include a regulating effect similar to the Cline. The Varsane/Perry "regulating" pumps do not regulate like the Cline. They allow the user to vary the pressure produced, but the higher pressure generated reaches the carb. The Perry/Varsane oscillating pump does not regulate like the cline. The output, the fuel pressure, however varies more than the "regulating" version, because the pressure increases with increased engine rpm.

How does the modeler know, or how can he test to find out, if the pump in use regulates like the Cline?

3. The engine or carb manufacturer designs the carburetor to operate in a certain pressure environment. Presumably the typical carb, intended for "normal" pressure will perform poorly at higher fuel pressures. Similarly, the carb designed to work with an unregulated pump will also perform poorly at "normal" fuel pressure.

How does the modeler know, or how can he test to find out, when the fuel pressure at the carb is outside design perameters?

I'd better stop here so you can grade my essay, before we tackle the next set of inferences.

GoNavy