From: earl@trsvax.tandy.com
Newsgroups: rec.models.rc
Subject: Webra t4-80 solutions
Date: 15 Dec 92 19:44:00 GMT
Nf-ID: #N:trsvax:1195667332:000:4007
Nf-From: trsvax.tandy.com!earl    Dec 15 13:44:00 1992



Webra T4-80 notes...

   Well...after perservering, I discovered that the little 3/8" long piece
of silicone tubing on the main needle valve was loose and allowed the engine
to leak air and fuel out of this area. I took a 1/2" long piece of standard
Bru-Line blue tubing and replaced the offending item. The engine then had
a much better ability to run right, and I could adjust idle mixture to a more
suitable setting.
   It still needs 15% nitro in the fuel due to it's lower compression ratio.
I am still waiting for a couple of "hot" heat range plugs to come in, as I had
to special order them, as none of the hobby shops stock them.
   It still won't idle below 3,000 to 3,200 RPM. With 3,300 to 3,500 being
quite reliable. MAybe after a few gallons of fuel it will idle better.

   Unofficial prop speed timings....
   Master Airscrew 12-8" prop      10,200 RPM
   Master Airscrew 13-6" prop      9,500 RPM
   APC  11-8" prop                 11,500 RPM
   APC  12-8" prop                 10,500 RPM

   The 13-6 will have to do as with the higher idle speed, I'll need a lower
   pitch prop to help keep the air speed down on landings.

   Webra didn't make it easy to set up their engine. I had to special order
   this engine, as none of the hobby shops have any demand for stocking them
   in the first place. According to the instructions that came with the
   engine...they said to leave the needle valves alone as they had preset
   them at the factory. Well after unpacking a obviously factory packed engine
   box, and bench mounting the engine, I discovered that the both needles were
   screwed in all the way, plus the idle stop was screwed in too far, and the
   barrel stop screw was screwed in far enough to tighten up and jam the
   throttle barrel. Anyway it took quite a while to get it running well enough
   to start figuring out what all the problems were. Then after getting side
   tracked, I discovered that the main needle was leaking air around a loose
   fitting piece of silicon tubing. After correcting that problem the engine
   now runs pretty good. Now I can wait for the weather out here to improve
   so I can go fly the plane it is in. But if your a beginner to model engines
   I highly recommend that you go with a OS Surpass, Saito, or Enya 4 cycle
   engine before getting one of these Webra engines. As you'l have to
   tinker with it and use up a lot of fuel and patience to get it to work
   right.  Once you do figure it all out, it does work pretty good though.
   Now it's time to find out how long it'll last before that overhead rotary
   valve or toothed belt drive wears out.

   I also tried out a new item a "one-way" valve on the muffler pressure tap.
   This worked quite well, but it' keeps the tank pressurized after you kill
   the engine. Thus you could easily flood out your engine if you aren't
   careful and pinch off the fuel inlet line to the carburator. On the Webra's
   4 cycle muffler, you can build up several PSI in the tank which could be
   risky as the fuel tank bulges out a lot from the internal pressure and might
   split open in the future. With all that pressure in the tank, you could
   put the tank pretty much anyplace you want, it sort of acts like a 
   replacement for a fuel pump. Since I didn't want to risk a split tank I
   opted to quit using the "one way" valve and go back to using standard
   medical hemostats when I fuel the model, on both the fuel inlet to the carb
   and on the muffler.


***********************************************************************


<This information is provided by an individual and is not nor should be
 construed  as  being  provided  by  Radio  Shack or Tandy Corp.  Radio
 Shack/Tandy Corp has no obligation to support the information provided
 in  any way. > 
						
						Earl W. Bollinger
						@ <earl@trsvax>


"You were in the Clone Wars!", said Luke excitedly.
"Yes", replied Obi Wan, "I was a DOS programmer. But that was before the dark
 times, before OS2."
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