RE: Why not a Webra engines thread?
 

Thanks for those files Jetpack. They will be useful.

Reading the Dynamix instructions I noticed two things. One, they were written by Yoda. Two, the section on the Idle mixture contradicts itself. At the end of the first paragraph in section 3 it states that clockwise richens and counter-clockwise leans. In the following paragraph it states the opposite.

David

RE: Why not a Webra engines thread?
 

[sm=bananahead.gif] Yep. I figured out you just have to remember the more you turn the thumb wheel in, the richer the idle setting because the throttle plate closes off more air while the mixture tube stays the same.

Sometimes I think Webra's other buisness is puzzle making.

RE: Why not a Webra engines thread?
 

Question.

I just finished restoring a used #1020 Blackhead marine. I noticed a difference between the carb barrel diameter and the carb body, which causes a step in the bore on the low speed side of the carb.

The barrel bore is 7mm and the carb bore is 8mm. A difference of 1mm.

First of all, is this the right size bore for this ccm, and second, is it mis-matched to the carb body?

Can someone check what their known sizes are for each of these parts?

Webra just lists the carb numbers, no real size reference to them and it's bugging the heck out of me until I know for sure these throat sizes are right for this engine.

RE: Why not a Webra engines thread?
 

I just checked the barrels on my 6.5ccm Blackhead, 10ccm Blackhead and Speed .61. All three carbs seem to use the same body. The 40's barrel measures 6.5mm, the 10ccm measures about 6.95 - 6.97mm and the Speed's measures 8mm.

It looks like Webra used the same carb body with different barrels for different engines. That's why the opening in the body is larger than your barrel. The 8mm barrel on my Speed .61 is the same size as the body.

David

RE: Why not a Webra engines thread?
 

JP...I have noticed that sort of mis-match on other engines carbs from that era...O.S. comes to mind first. (I'm thinking of the air bleed carbs w/ Brass barrels of the .20, .25. .35, .40 )

RE: Why not a Webra engines thread?
 

Thanks guys. It was another question I wasn't really excited about having to write Webra about.

RE: Why not a Webra engines thread?
 

new webra racing80 and new 91P5 fuel pump

RE: Why not a Webra engines thread?
 

Hello guys,
I have a Webra 120 that I got with a finished Extra 300. The engine has cost me 4 airplanes. I'm about ti give up with it. It runs OK a time or two, but later keeps flaming out during flight. What I have noticed is that it cuts off after some -G manoeuvers. Some fligths seems to be rich and later you can not see a trail of fuel. Fuel is Powermaster, 10% Nitro and 18% blend.
It's mounted sideways with Pitts style muffler which is filled with steel wool, trying to increase the tank pressure.
Any ideas or suggestions?
Thanks for your time
Rene

RE: Why not a Webra engines thread?
 

Don't own one so I'm guessing. If your carb is anything like mine is in the last picture, the low speed needle valve is loose inside the threads of the throttle barrel.

As I close the idle needle into the spray bar hole, I can wiggle it to touch either side all around the opening with my fingers.

Anytime I touch the adjustment on the needle, it affects how the taper of the low speed enters the center of the hole in the spraybar. Plus anytime there's slop in carb threads, there's air leaking past it.

Try inspecting your carb needles, and if there's any slop or such like I explained, try either using some teflon pipe tape and closing it up that way, or use a trial-and-error cut of fuel tubing to block off the air and keep the slop out of the threads. The fuel tubing trick is standard Webra practice, and if your carb doesnt still have it on there, they show it on their carb small parts kits.

Doing high G manuvers tells me that engine is doing some high revs and then backing down from it. RPM vibrations change a lot when that happens and could be changing the location of your idle screw. Not necessarily its in and out location, but how well centered it stays.

Another big tip is taking a few minutes and bending the spring clip of it so it affects the screw the least. Each side of that spring needs tweeking to keep the needle riding proper, and with the right tension. Stock stamping and assembly of it doesn't have any accuracy right out of the box, and with loose threads on the needle throws it way out of whack.

Fuel delivery problems fall into your explaination also, so check your tank and pressure lines.

RE: Why not a Webra engines thread?
 

JP, where do you buy those nifty little nipple caps?:D

David

RE: Why not a Webra engines thread?
 

-


What you are describing is not an engine problem, but a fuel tank problem.

You've read all of the discussions about fuel tank height, most likely. The next thing to ponder is vibration isolation, which will provide the symptoms that you are describing. If everything is buttoned up tight on the engine with no air leaks and the engine is in normal/average running condition and your tuning is not out by some gross amount, it is pretty much a fuel tank problem.

Some folks feel that if the model came through with the fuel tank solidly mounted as recommended by the manufacturer, then it must work correctly when mounted that way. I have seen this assumption kill many models because of unanticipated deadsticks. One must keep in mind that some of the folks designing these models are very young and inexperienced modelers. Many buy models based upon specs and the particular way the model is covered. None of this has anything to do with how well engineered the model is or isn't.

Glow engines are simple devices. Provide them with the proper mixture of fuel and a working glow plug and they will not stop unless maladjusted, a plug fails OR THE FUEL TANK IS HARD MOUNTED AND CAUSING BUBBLES THAT MAKES THE ENGINE STOP.

I have seen many mistakes in Chinese (and other countries of origin) products. Many are correctable by the end user. It is time to go over the fuel tank installation and stop picking on the engine. In good condition, a Webra 1.20 two-stroke is an extremely reliable engine. Look elsewhere for the cause of your deadsticks.


Ed Cregger

RE: Why not a Webra engines thread?
 

Thanks for the suggestions and I'll check on them as soon as the temperature here in Texas gets over freezing!!

RE: Why not a Webra engines thread?
 

Thanks again! I'll try this too. Actually I had the same problem with 2 different A/C and a couple of different fuel tanks and again after I switched to an Evolution 1.00. The only constant is the HARD MOUNTING FUEL TANK!!!!!

RE: Why not a Webra engines thread?
 

Santa got me an Outlaw flying wing for Xmas. I want to put a webra 36 speed in it (the OS .32 and the Webra 36 speed are recommended engines.) Because of the orientation in the model, they recommend rotating the carb so the needle valve is protected. Can I re-orient the fuel inlet nipple as well, so it is not facing forward when I rotate the carb 180 degrees?

The webra site indicates the carb for the 36 speed is the TN II. Thanks in advance.

RE: Why not a Webra engines thread?
 

If it is the kind in the first picture, yes - but it's not easy. You have to dis-assemble the whole carb to where your left with just the body and the brass fuel assembly.

The assembly is pressed into the carb body, so you'll have to press out the assembly by putting a socket inside, and then using a larger socket to clear the brass, and tap it out.

It doesn't pay to heat the body up because you won't be able to heat it up fast enough where the aluminum expands before the brass heats up. They'll both have the same expansion rate, so just press it out.

It will be tricky to do without marking things up, but its possible to do. I had to replace a broken brass assembly before.

The fuel nipple is a problem because it will be in the way, but it can be heated up and de-soldered OR you can attempt to work around it by using a good heavy crescent wrench to straddle around it, and tap on the crescent.

If the OD of the intake and the neck is the same, you could use those two diameters to rest the crescent but you run the risk of marking or distorting things up.

Thats the only way I can think of. Hope someone has a better idea than this because its not easy, its frustrating, and it can really cause some damage if you're not careful and take your time doing it.

RE: Why not a Webra engines thread?
 

thanks jetpack,

I found a thread on flying giants that detailed exactly what you said. I really want to go with the webra 36 and didn't want to go with a poorly performing substitute. thanks for the help. Now to find a hobby store that sells them...

drew

RE: Why not a Webra engines thread?
 

Drew, a number of folks here have reported good service from:

http://www.swanyshouse.com/engines/engines.aspx

David

RE: Why not a Webra engines thread?
 

Are they the US Webra distributor now?

Thanks,

Ernie

RE: Why not a Webra engines thread?
 

Ernie, I believe Paul's Model Supply is the US importer/distributor. I have ordered parts for older Webras from him a couple of times.

David

RE: Why not a Webra engines thread?
 

I have a crankcase of a Webra 61 seed F , so i made the rest of the components transforming the engine to a reer induction ,all is fine up til now ,one problem came when at the piston , i just could not detect the measurments inner and outer, length and cut away.can anybody provide me with this information???? happy new year to all.

RE: Why not a Webra engines thread?
 

Andrew,
I have exactly the same airframe and engine as you. Yes, you can turn the carb 180 deg to put the intake at the top. The fuel nipple will then be at an angle and facing somewhat toward the prop. Don't worry about that; the fuel line will attach perfectly and not kink. You don't need to separate the press-fit carb parts, and it isn't advisable without the proper tools and equipment. Just flip the carb around and fly it. I think you can find some pics of my Outlaw configured like this on the "extream speed prop planes" forum.
Arthur

RE: Why not a Webra engines thread?
 

I am a powerboater and wondering if the case on a 61F can be turned around to be a rear intake / front exhaust engine. Is the case symetrical in this respect? Is the cylinder bore on center of the case faces? Are the diameters the same on each end of the case?

I realize there might be some performance loss due to the angle of the boost ports being reversed away from the intake side, but it sure seems like a nice engine to convert to boat use.

Since I'm here I'll add more Webra documents that they have sent me. These are for their carbs.

RE: Why not a Webra engines thread?
 

Back to the little ol' 3.5 Glowstar. I picked one up on auction that has really excellent compression...you can turn it to TDC and just leave it there several seconds, and then push the prop and get a nice "plop" as it snaps around. Like a good old Enya.

I ran mine on Omega 5% nitro with quite a lot of added castor. Temp 45 degrees. It hand started on the first flip after choking. It throttled down well, but died when I opened the throttle. Discovered previous owner had the air bleed screw covering half the hole. I don't know why they even make them adjustable because I always wind up with them wide open, which is what I did to this one.

So tried again, and here I have to confess to changing two variables at once. I know, shame on me. I switched to an Enya #3 plug. After those two changes, I could throttle it down and bring it back up again, but it would hesitate unless I did it slowly.

On an old TF 9x4 I got 11, 400. With a Zinger 10x4, 9,000 and not steady. Back down to an old TF 8x4, 13,200.

That's with an old Semco twin pipe muffler. I didn't try open exhaust. It's not as strong as my Enya .19 V, but it's not too bad either. It would be a perfectly usable engine on a vintage design.

Jim

RE: Why not a Webra engines thread?
 

Andrew,
I just noticed an old post of your's about the Outlaw and the .36 Webra. How did it work out?

RE: Why not a Webra engines thread?