OS 160FX setup

[Bob Richards]

Running crankcase pressure was a very good thing for control-line engines. I had a ST .15 that would not run well without it, but ran great in every attitude with it. 
 
One problem with RC application is the fuel metering of the an RC carb does not work well with the pressure. Also, when the crankcase pressure drops as the engine idles down, there is a good chance that raw fuel can run back from the tank and into the crankcase, which will flood the engine. With muffler pressure, a little raw fuel in the muffler won't hurt anything. If you put a one-way check valve in the pressure line, then you won't get the variable pressure to the fuel tank that you really need for the carb to work well.
 
I've used one of the Cline regulators, and it seemed to work very well, but I did not get a chance to use it very long. I was testing an MVVS .61 for pattern. (Great engine!). One problem was that the carb had to be modified slightly. The carb was designed for muffler pressure, but the Cline regulator reduces the fuel pressure to atmospheric. I had thought about running a muffler pressure line to the vent (atmospheric) side of the regulator diaphragm, but never had a chance to try it out.
 
For the life of me I can't understand how the hopper tanks work. If the main tank drops 6 inches, then you still have to pull fuel from 6 inches, with or without the hopper tank. The only way I can think of it working is if there is some air in the hopper, then momentary changes in the main tank height won't be felt at the carb, but extended up/down lines would be. Still, it seems to work, and may be the route I would go. I like simple.
 
Bob Richards.


randy10926 at comcast.net wrote:
Just wondering -
 
Why run the pressure tap from the pipe instead of the backplate?  Also I run a greeve pipe which has no visible high point that I notice.
 
Randy
 
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----- Original Message ----- 
From: Karl G. Mueller 
To: discussion at nsrca.org 
Sent: Thursday, December 02, 2004 11:10 AM
Subject: Re: OS 160FX setup


Wayne,
 
I haven't used a pump or regulator since I got the first O.S. 160FX.
Two seasons on the first with the original bearing in a heavy 2M Star.
4oz. header tank behind fire wall and 16oz. tank just in front of wing tube.
Pipe pressure from high point of pipe into main tank. No need for any
pump or regulator. Consistent runs and excess power every flight with 
unlimited vertical. 
16.5 X 12 APC, Fourstroke Y.S. plug, Mac's #1090 pipe with small diffuser-
aftermuffler added to stinger. You can guess who's header. Very quiet setup.
Will run on any fuel from 15-30%  without any noticeable change in power.
 
Karl G. Mueller
kgamueller at rogers.com

 
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