Glow Engines Discuss RC glow engines

Old Webra 32

Reply

Old 05-10-2007, 06:39 AM
  #1  
John@FLYRC
Member
Thread Starter
 
Join Date: May 2003
Location: Bethel, CT
Posts: 70
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Old Webra 32

Good Morning Gentleman -- Here I am again -- Same old fart -- New problem.

I recently got an old 3-D plane with, I believe, an older Webra 32 on it. I cleaned it up, oiled everything in sight and put it on the test stand. After a few tries I got it started and ran it for a few minutes at about 1/4 throttle. It got hot as the devil and stopped. To me this means too lean but I haven't a clue on setting Webra carbs. I read Dar's explanation of setting up a .40 but it didn't give me a starting setting for the high end. Right now the main is about six turns open. This is a lot more than any of my OS, MDS, or Saito engines. I m afraid to run it again until I am more knowledgeable. Oh yes, I am running 10% nitro, 18% synthetic and 2% castor.

Any guidance will be appreciated. While I wait I will continue reading the "Webra" threads
John@FLYRC is offline  
Reply With Quote
Old 05-10-2007, 07:30 AM
  #2  
DarZeelon
Senior Member
 
DarZeelon's Avatar
 
Join Date: Apr 2003
Location: Rosh-HaAyin, ISRAEL
Posts: 8,913
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

John,


At 1/4 throttle (actually up to ~3/4), the metering of the fuel is done by the low-speed needle.

Your engine probably has the TN II carburettor and it is the needle in the throttle-arm of the carburettor.

Although the control is by the low-speed needle; if the high-speed needle is closed too far, or there is some kind of obstruction in the fuel system, the engine could suffer a 'lean-run' at this part throttle setting too.

The Webra manual is wrong (!!!!) in stating the secondary needle only controls the idle mixture... It was probably written by their marketing department...

All actions described below must be done with the engine shut-off!!!

Open the high-speed needle 2.5 turns from the fully closed position. Connect a piece of fuel-tubing to the nipple, open the carburettor to full and blow through the tubing, while turning the high-speed needle. You should feel the flow increase, as the needle is opened further and vice-versa when it is closed. This will rule out an obstruction inside the carburettor.

Now, fully close the low-speed needle and close the throttle to idle position (about 1 mm eye-slit). Blow through the tubing, while gradually opening the low-speed needle until you can just hear the hissing... It should be 2-2.5 turns open.
Keep blowing and open the throttle gradually. You should feel the flow increase as the throttle as opened and decrease as it is closed.
This is the fuel-mtering function of the low-speed needle.

Visually inspect the fuel-lines, also inside the fuel tank meticulously, to ascertain there is no obstructions, sharp bends, or kinking in the fuel-lines.


Although the manual allows up to 15% nitro in the fuel, all Webra engines I have ever seen were happier with 5-10% nitro.

So from that perspective the fuel is good, but the synthetic lubricant in most US made fuels, is not as good as Sach Aerosynth II/III, or Aerosave, that Webra subscribe. So I suggest that you use a fuel with more castor oil, like Sig Champion, or Morgan's Omega.


What is the point of running the engine continuously at 1/4 throttle?

Get the engine to full power and adjust the high-speed needle, to about 1/8 a turn rich of peak and the low-speed needle to a perfect response and transition.
DarZeelon is offline  
Reply With Quote
Old 05-10-2007, 07:59 AM
  #3  
Dr1Driver
Senior Member
 
Join Date: Jul 2002
Location: Spartanburg, SC
Posts: 3,770
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

The low speed needle on the .32 interacts with the high speed needle a lot. Make sure it open enough, at least 1/32" away from the end of the spraybar. Webras like nitro, too. You can run up to 25% with no problems.

Is it possibly worn out? Engines often get lean when that happens.

Dr.1
Dr1Driver is offline  
Reply With Quote
Old 05-10-2007, 09:55 AM
  #4  
DarZeelon
Senior Member
 
DarZeelon's Avatar
 
Join Date: Apr 2003
Location: Rosh-HaAyin, ISRAEL
Posts: 8,913
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

David,


I don't think you are right about Webra engines 'liking' nitro...

Even in cool Austria, the manufacturer recommends a maximum of 15% and in hot Israel, even 10% often proves to be too much.
You can richen the mixture to avert over-heating and detonation on 15%, but then, the engine will make just as much power and idle as smoothly, with just 5%.

Our engines, including those from Webra, were originally designed to use a 80/20 mix of methanol and castor oil - no nitro...

Only the drag-race crazed, 'top-fuel' American crowd made nitromethane a substance one almost 'can't do without'...
Yet, "As a general rule all Webra motors will run properly on "straight" fuel, i.e. without nitro-methane".

This is word-for-word from the Webra English language manual.


As to your remark on wear being the culprit... It could be so.
I tried to start a friend's .40 Dykes ringed Webra, that had the ring stuck solid and zero compression...
I couldn't even prime the engine, not even by plugging the exhaust...
DarZeelon is offline  
Reply With Quote
Old 05-10-2007, 10:44 AM
  #5  
Dr1Driver
Senior Member
 
Join Date: Jul 2002
Location: Spartanburg, SC
Posts: 3,770
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

I don't think you are right about Webra engines 'liking' nitro...

I've owned 4 Speed .32s, two Speed .40s, and one Speed .50, and they all love to run on at least 15%. The .32s on 25% are awesome. I get great power, reliable idle, mo detonation, and the only downside is they tend to start backwards.

Dr.1
Dr1Driver is offline  
Reply With Quote
Old 05-10-2007, 11:00 AM
  #6  
DarZeelon
Senior Member
 
DarZeelon's Avatar
 
Join Date: Apr 2003
Location: Rosh-HaAyin, ISRAEL
Posts: 8,913
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

Dr.,


You may be right, but I can only judge by my own experience in my own country's weather.

I had one Webra (a .40 Speed) and ran it on 5%.

Starting backward is usually caused by over-priming... but also by detonation... so you may actually be experiencing an effect of high nitro.

I do suggest that you try running those Webras that you own, on 5% nitro.

You may be surprised by the performance (or by the lack of difference from your old fuel) and by the much lower fuel consumption.
DarZeelon is offline  
Reply With Quote
Old 05-10-2007, 11:30 AM
  #7  
blw
My Feedback: (3)
 
blw's Avatar
 
Join Date: Mar 2004
Location: Opelika, AL
Posts: 9,447
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

That doesn't sound very flattering, especially to someone like me who enjoys drag racing a lot. I'm not sure about now, but drag racing has been very big in other countries like Sweden and Australia. I've personally seen a large interest in it in Europe.

Nitro isn't very expensive here for whatever reasons there are, but shouldn't be a reason to look down on people who use it.
blw is offline  
Reply With Quote
Old 05-10-2007, 12:05 PM
  #8  
Dr1Driver
Senior Member
 
Join Date: Jul 2002
Location: Spartanburg, SC
Posts: 3,770
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

Further posts from Dar blocked. Bye.

Dr.1
Dr1Driver is offline  
Reply With Quote
Old 05-10-2007, 12:22 PM
  #9  
DarZeelon
Senior Member
 
DarZeelon's Avatar
 
Join Date: Apr 2003
Location: Rosh-HaAyin, ISRAEL
Posts: 8,913
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

Barry,


I am looking down on no-one.

It is just that 'real' engine guys will easily make an engine run well on FAI fuel...
Only those who are less patient, or less talented, actually need the wider acceptable range, higher nitro gives the needles.


And it just happens that in the USA the price of nitro is low enough to allow its use in percentages of 15-30, while most of the world uses FAI, or 5%... Are American modelers spoiled? Could be, but it is more a matter of costs.

And I believe anyone in this forum should be talented enough to use FAI, or 5%, unless it is a YS (15%+), or a race engine designed for 70% nitro...

If you use FAI fuel and adjust your engine rich of peak, and it becomes too lean when you put the plane in a nose-up attitude, maybe the tank is too far from the engine... Using 15% nitro could make it more tolerable to these mixture changes.

But hey, building your plane properly to begin with makes this unnecessary...
DarZeelon is offline  
Reply With Quote
Old 05-10-2007, 12:42 PM
  #10  
MikeL
Senior Member
My Feedback: (3)
 
Join Date: Mar 2002
Location: Bloomington, MN
Posts: 3,282
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32


The two of you have had different experiences. Is it possible that Webras imported into the US have a head shim in place that allows them to comfortably run higher nitro?
MikeL is offline  
Reply With Quote
Old 05-10-2007, 07:34 PM
  #11  
John@FLYRC
Member
Thread Starter
 
Join Date: May 2003
Location: Bethel, CT
Posts: 70
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

WOW Sorry Guys -- Looks like I stirred one up without trying. Thanks to you all. Dar -- I mix my own fuel and favor low nitro. 1.) I am not a very proficient flyer so "right on the edge" power for me is not required. I do not need high performance from my engines. 2.) Nitro is not terribly expensive here but it costs considerably more than methanol. As I am retired and on a limited income the less expensive the fuel the more I fly. 3.) My minor knowledge of chemistry tells me there are more calories in a liter of meth than a liter of nitro. So If you can get it to run why get the extra energy and save the money?

I am tired tonight but tomorrow I will post a pic or two and may give your instructions a try. At this point in time I have only 10% nitro mixed but if I can push it down I will add meth and oil to a guart or so and test. I assume FA1 is the name of a no nitro fuel. Boy, if I could get my engines to run on that I would save a bundle!
John@FLYRC is offline  
Reply With Quote
Old 05-10-2007, 09:37 PM
  #12  
blw
My Feedback: (3)
 
blw's Avatar
 
Join Date: Mar 2004
Location: Opelika, AL
Posts: 9,447
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

I didn't mean your comments Dar, but the comments you quoted are demeaning to me and that's why I made mine.

I'm not sure that I want to run FAI fuel in anything unless I'm flying in competetion due to the 20% all castor rule. I have been running 15% nitro for years because it is cheap and probably the most common fuel in this area at 4 hobby shops that I go to. You can be sure to get that, but 5 or 10% Omega may not be in stock. I tend to buy it by the case, so I want what I use when I buy it. My last purchase was $40 for a case of Omega 15%.

I agree that a reasonably competent person could tune engines without nitro, but the fact is some engines are intended for some nitro. Why bother in my case? There is a little bit more power with it, and they do run smoothly with nitro. Live and let live.

We have gotten off track with a lot of help from me.
blw is offline  
Reply With Quote
Old 05-11-2007, 07:07 AM
  #13  
John@FLYRC
Member
Thread Starter
 
Join Date: May 2003
Location: Bethel, CT
Posts: 70
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

Think I figured out to upload pics Here goes. On the 1/4 throttle -- It was just place to start. I assume the hi speed needle is the one next to the nipple as on my other engines. It must be obvious I have never seen a carb like this before
Attached Thumbnails Click image for larger version

Name:	By76255.jpg
Views:	13
Size:	95.4 KB
ID:	682056   Click image for larger version

Name:	Av69504.jpg
Views:	14
Size:	61.2 KB
ID:	682057   Click image for larger version

Name:	Ns45492.jpg
Views:	9
Size:	86.5 KB
ID:	682058  
John@FLYRC is offline  
Reply With Quote
Old 05-11-2007, 08:06 AM
  #14  
DarZeelon
Senior Member
 
DarZeelon's Avatar
 
Join Date: Apr 2003
Location: Rosh-HaAyin, ISRAEL
Posts: 8,913
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

John,


That is a Dynamix carburettor!

According to their manual, it needs a relatively high fuel pressure to work properly.
It will not work on fuel suction, but muffler pressure may be enough.

The high-speed needle (it is what you think it is) must be open 6-8 turns (not 2-2.5 like in the TN II). Start with 7.5 and close to find peak RPM.

The low-speed 'needle' (the knurled nut at the end of the throttle slider's threaded rod) is turned in (clock-wise) to richen the low-speed mixture and out to lean it.
This carburettor is not an air-bleed type, but this adjustment determines the position of the eye-slit in the fuel-metering plunger rod (surrounded by a spring), relative to the throttle barrel.

This 'plunger' is also said to act as an accelerator pump, to aid transition from idle to full, but in lieu of a check-valve in the fuel feed route, I doubt it actually works as such...

Besides, glow engines don't need this to function properly. It is too much fuel in the low-end that usually causes 'engine infidelity'...
DarZeelon is offline  
Reply With Quote
Old 05-11-2007, 08:13 AM
  #15  
Sport_Pilot
 
Sport_Pilot's Avatar
 
Join Date: Jan 2002
Location: Acworth, GA
Posts: 16,915
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

Only the drag-race crazed, 'top-fuel' American crowd made nitromethane a substance one almost 'can't do without'...
Yet, "As a general rule all Webra motors will run properly on "straight" fuel, i.e. without nitro-methane".
One can do without beer, but geez is it GOOD! Same with nitro.
Sport_Pilot is offline  
Reply With Quote
Old 05-11-2007, 08:16 AM
  #16  
Sport_Pilot
 
Sport_Pilot's Avatar
 
Join Date: Jan 2002
Location: Acworth, GA
Posts: 16,915
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

It is just that 'real' engine guys will easily make an engine run well on FAI fuel...
Only those who are less patient, or less talented, actually need the wider acceptable range, higher nitro gives the needles.
I have several engines that run well with no nitro, and I have run them that way, though most of the time I use 5%. With no nitro the needles are sensitive and sometimes very difficult to adjust in hot weather. A cold plug helps. An engine desiged for some nitro just runs better with more power with only a small amount of nitro say 10%.
Sport_Pilot is offline  
Reply With Quote
Old 05-11-2007, 09:05 AM
  #17  
brewski
Senior Member
 
Join Date: May 2006
Location: CAMDEN, TN
Posts: 496
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

blw,

where do you find $40 per case fuel? I am assuming it is a 4 gallon case. geez, it cost me $10.50 per gallon to home brew 10% nitro.
brewski is offline  
Reply With Quote
Old 05-11-2007, 04:36 PM
  #18  
dennis
My Feedback: (90)
 
Join Date: Jan 2002
Location: Minersville, PA
Posts: 1,855
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

It may suprise most modellers to know that most new motors made run quite well on 5% nitro. Use what you like but 15% will not buy you much in improved performance. What it does is let you burn more fuel.You need to open the needle valve more to contain the heat generated by the additional power.It does however let you get a good idle without having to work too hard at it.
truthfully using 15% nirtro because it makes your motor run better is at this point in time really is not true anymore.
Many speed events are limited to 10% nitro and are going faster then the days of 65% nitro.
dennis
dennis is offline  
Reply With Quote
Old 05-11-2007, 07:05 PM
  #19  
John@FLYRC
Member
Thread Starter
 
Join Date: May 2003
Location: Bethel, CT
Posts: 70
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

I have a chance to get a TN II. It looks like the barrel diameters are the same. Do I want to go that way? I got the engine to run pretty well today. The transition is still a little hesitant. The thing I haven't figured out is I can lean the low speed by going too far in either direction, in or out. The shape of the V-groove in the side of the brass tube makes me think that all the way out and then adjust it inward is the right way because when you open the throttle you increase the width of that opening. As may be, I will play with the adjustment on both sides. Dar -- Thanks for the 6-8 turn tip I opened and opened from 2 1/2 turns but haven't checked to see how far open I got it. QUESTION : How do you feel about 9 X 6 vs. 10 x 4 prop on this 32. Alternatively do you have another choice I might try?

Thanks again to all who answered. I read it all and will report on how the engine runs (assuming I don't bury it in the first couple of flights) and how it feels about different fuels -- Admitting my bias toward low nitro.

I too mix my own 10% and it is about $11 per gal.
John@FLYRC is offline  
Reply With Quote
Old 05-11-2007, 07:36 PM
  #20  
Hobbsy
My Feedback: (100)
 
Hobbsy's Avatar
 
Join Date: Dec 2001
Location: Colonial Beach, VA
Posts: 18,358
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

http://www.webra-austria.at/download/motor_e.pdf
John, here are instructions for all the Webra carbs, this is a PDF, the DynaMix is item #6.
Hobbsy is offline  
Reply With Quote
Old 05-11-2007, 08:28 PM
  #21  
jetpack
Senior Member
My Feedback: (1)
 
jetpack's Avatar
 
Join Date: Oct 2002
Location: Hobart, IN
Posts: 2,476
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

I have rebuilt five of these carbs, and will share my thoughts on how to set one up. If you are working with a second hand motor, or have moved the mixture tube arm in relation to the mixture barrel, you should look to see if the mixture tube is properly orientated and it's travel points adjusted.

If you slide out the slide plate and mixture tube assembly from the carb base (such as you would for cleaning) you will be familiar with the design of the tapered V-groove and fuel hole.

The V-groove needs NOT to be rotated in any way other than perpendicular to the carb bore. If it is slightly pointed upwards, it will blow back the fuel supply. If it is pointed downwards, it will not atomize properly, and you will not find a good needle setting.

The V-groove at WOT should show even on both sides of the cut-out of the mixture tube barrel with the fuel orifice in the center location.

Closed throttle travel should allow the mixture tube to completely hide the very end tail of the V.

My experience with my five carbs show the factory fits the mixture tube flush or slightly above flush as it is mounted in the mixture arm with set screw. Looking only at this does not assure the tube is mounted correct radially, however and must be checked.

These carbs do need pressure to run, they do not pull enough vacuum to draw fuel. If going with muffler pressure only, and not a pump...fit at least a 5/32" fuel line to the carb.

I included an older working drawing of mine for a 7.5mm carb from a Speed 61 (it has since been revised - reference only). The drawing shows the fuel hole in the mixture tube traveling one hole distance away from the edge of the barrel, it is simply a way I have referenced my dimensions. It should locate right at center at WOT.

The smaller carbs have their mixture tubes drilled on center instead of a back channel milled into the bar, and the fuel hole does not travel completely through as do the channeled type.

This radial orientation is critical and has a major impact on the ability for the carb to have a good range of performance.
Attached Thumbnails Click image for larger version

Name:	Ki19377.jpg
Views:	16
Size:	47.8 KB
ID:	682519   Click image for larger version

Name:	Bw71384.jpg
Views:	11
Size:	41.1 KB
ID:	682520  
jetpack is offline  
Reply With Quote
Old 05-11-2007, 09:21 PM
  #22  
piper_chuck
My Feedback: (12)
 
piper_chuck's Avatar
 
Join Date: Jun 2004
Location: Columbia, SC
Posts: 8,039
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32


ORIGINAL: Dr1Driver

I don't think you are right about Webra engines 'liking' nitro...

And I don't think you know what a Webra likes. How many have you owned and run weekly, Dar? I've owned 4 Speed .32s, two Speed .40s, and one Speed .50, and they all love to run on at least 15%.
My .32 runs pretty darn well on 15% too.
piper_chuck is offline  
Reply With Quote
Old 05-12-2007, 01:23 AM
  #23  
DarZeelon
Senior Member
 
DarZeelon's Avatar
 
Join Date: Apr 2003
Location: Rosh-HaAyin, ISRAEL
Posts: 8,913
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32


ORIGINAL: John@FLYRC

...The shape of the V-groove in the side of the brass tube makes me think that it's all the way out and then adjust it inward is the right way, because when you open the throttle you then increase the width of that opening.
John,


That eye-slit should open, i.e. increase the orifice size, as the throttle is opened. When close to full, the size should no longer increase, since fuel pressure is increased. It balances out and your engine will get the right amount of fuel.


How do you feel about 9X6 vs. 10x4 prop on this .32.
Those sizes are right. The larger diameters and smaller pitches are for slow-flying, high drag models and the smaller diameter props with high pitches are for fast models. The 8x8 size is also good for really fast planes.

But experimentation is a part of this hobby. You rarely find the ultimate prop, just on recommendations...
DarZeelon is offline  
Reply With Quote
Old 05-12-2007, 06:29 AM
  #24  
John@FLYRC
Member
Thread Starter
 
Join Date: May 2003
Location: Bethel, CT
Posts: 70
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

BLW -- Out of curiosity what does nitro cost in your area? Thanks
John@FLYRC is offline  
Reply With Quote
Old 05-12-2007, 06:36 AM
  #25  
John@FLYRC
Member
Thread Starter
 
Join Date: May 2003
Location: Bethel, CT
Posts: 70
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Old Webra 32

Dar -- Thanks -- will try to fly it today.

Amen to testing -- I spent my professional life in semiconductor research -- from epitaxial germanium to the first pulled single single crystal silicon. (3/4" -- they now pull 15" crystals) and the first IC (50u lines ! ! ! -- they are now doing 0.3u stuff)
John@FLYRC is offline  
Reply With Quote

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service