.049 Fuel. . . and various questions - Page 7 - RC Groups
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Dec 08, 2012, 12:53 AM
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boingk's Avatar
Use a glow ignitor with an attachment for alligator clips. I use these:



Put a rechargeable AA battery (I like Turnigy LSD's, Eneloops or Energizers) into the glow plug starter and you're good to go. Plug it into the 'glowplug' end of the wiring assembly and strip the ends and crimp on alligator clips. Attach clips to Cox engine, go for your life.

Never use an electric starter on these engines, way too easy to hydrolock them.

Cheers - boingk
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Dec 08, 2012, 10:42 AM
Team Compass/KBDD Team Pilot
Ah Clem's Avatar
BoingK is right.

You don't need a starter with that engine.

You don't need a chicken stick, either-let your newly repaired Rotomatic starter do its job.

Open the needle 4 to 4 and a half turns.

Force the fuel through the line, into the carb by pressurizing the fuel line (cover the vent and squeeze the bulb or fuel bottle) until the venturi fills up about half way.

Squirt fuel on the exhaust port.

Make sure the glow plug is tight and is glowing a bright orange.

Turn the starter counter-clockwise gently until it stops, then let it go.

It may take a few tries.

With the right fuel and mixture setting, and broken in, these will start in a few tries.

What fuel are you using (I know it is somewhere in this thread)?

Remember what I said about the starting fluid, very early in this thread. That made a huge difference.

These should start and run well. This is a wall broken in Wen Mac Mk XIII (very similar to your engine. It usually starts on the first of second try:

WenMac P-39 (1963 Vintage) (2 min 13 sec)
Dec 09, 2012, 09:25 PM
Registered User
PyroMan's Avatar
Okay, first off I guess I forgot to tell you all that my Rotomatic spring is broke again. I've fixed it about three different times in attached the spring three different ways. Only once was over-tightening the spring the cause of the failure. I even fixed it again today but it didn't last long. So as of right now I am done with repairing it. I may see if I can do a cox starter spring thing. Where the spring is on the outside and attaches hooks on the prop. It seems a whole lot easier than what I'm doing now.

Anyways, I tried to start the engine again this afternoon with a 'little' better luck. Ah Clem, I am using SIG Champion fuel. It has 25% nitro and 20% oil (half castor, half synth). I filled up my fuel tank and using a chicken stick flipped the propeller and adjusted the needle valve for about 45minutes to an hour. It 'popped' a lot. Like it would pop like the fuel ignited but it wasn't enough to get the engine started or even flip the propeller a few times. I did get the engine to do about 5-10 revolutions on its own about 3 different times, but that was the closest thing to starting the engine when using a chicken stick.

Now I know you guys said not to use an electric starter, but I really really wanted to get the engine running and I felt like if I could just get the thing moving a little that it would kick off. So I went and grabbed my starter and tried it out. On three different occasions I got the engine started, but not for long. This is how it went. . . I used the E-starter for about 1-3 seconds and when I removed it from the engine the engine would continue running. It would be slow and the sound was low pitched. After about a second of the slow rpms, the engine would start increasing rpms and get to the point where it had that high cox-engine sound to it. It would stay high rpms for maybe 3 seconds, then slow down and die. It did this on three separate scenarios. Any suggestions of what to do from here?

I tried fuel with and without starting fluid. The starting fluid I have is the cheap stuff from WalMart. How much should I add to the fuel? I don't want to spray it into my full container of fuel. What I did today was when I sucked up my plain fuel with my syringe I left a little space and then sucked up some starting fluid into the syringe and shook the syringe to mix it up. I don't know exactly how much I added, just a little.

Since my needle valve broke and I have fixed it, I feel like my 4 turns out doesn't equal the same as you guys' 4 turns out. So, could someone with the same-ish engine (Ah Clem hint hint) tell me how many turns it takes to fully screw in your needle valve? That way I can figure up a rough estimate on how many turns out on yours equals the same amount out on mine. For example, if it takes 12 turns to completely screw in your needle valve but it only takes mine ten, then if you say to set the needle valve to 4 turns out, for me, it would really be 2 turns out.

Dec 09, 2012, 09:58 PM
Team Compass/KBDD Team Pilot
Ah Clem's Avatar

The needle has to turn in until it stops (fully closed), then opened four full turns. The the needle is damaged, it should be replaced. They come up on Ebay every once it a while.

For that matter, entire engines come up on EBay fairly frequently. Even a junk one can be a good source of parts (including the starter spring (whoever had your motor probably abused it, as it is very rare to have one fail in normal use, at least from my experience).

As far as the starter fluid goes, the stuff I have is half ether (I forget what the other half is). I will get it out tomorrow and get the brand name for you.

I did not know how much to use either (ether). I had a half full quart bottle of Glow Plug Boy fuel and shot two really short squirts of it in. Non-scienitific, I know, but it worked. That P-39 in the video usually starts on the first or second flip of the starter.

Using an actual electric starter may not be very good for that engine, as it is not designed for a reversed thrust load (I don't know for sure). Flip starting those is not as easy as with the stock starter, although you can do it.

If the motor speeds up and dies, it is too lean.

If it slows down and dies, it is usually too rich.

When it starts at four full turns, it will be too rich at first, gradually turn the needle in and it will start to run faster. You want to run it at just under the full, two cycle scream (honk). That way it will be rich enough to run the whole tank out (notice the P-39 sounds blubbery rich at first, then screams pretty good toward the end of the flight/tank).
Dec 09, 2012, 10:26 PM
Registered User
GliderJim's Avatar
Too me it sounds like when the engine first starts it's a little flooded. Once it burns off some of the excess fuel it leans out and starts to run well, but then runs out of fuel and stops again. The reasons for it being flooded could be from excessive priming, or from having the fuel tank too high so that fuel is slowly siphoning into the engine. I don't think the needle valve is open too far or it wouldn't lean out and stop...unless you're not drawing fuel at all.

For testing purposes I would put the top of the tank even with or just slightly above the needle valve. That way you don't have fuel running in and flooding the engine, but you also don't have fuel running back out to the tank. In that situation, if you get it running and it still speeds up and then quits, then I would think you should open the needle valve even more, although to be honest 4 turns seems like a lot to me.

Better yet, leave the tank disconnected. Prime the engine and try to start it. You should be able to get it to start and run off the prime for a couple of seconds. Once you've figured out to get it to start off the prime consistently, then you're ready to connect the fuel line and try again. If you have the same trouble, then try opening up the needle valve another half turn. If it gets worse go the other direction.

Regarding the electric starter - I feel your pain. I have a 1/2 a starter that I use sometimes. Be extra careful the engine is not flooded when using one since you could bend the rod if it is. Also, as mentioned previously, the engine wasn't designed with those forces in mind, so it may wear prematurely in places you wouldn't expect.

Take all of this with a grain of salt as I have no experience with that engine in particular. I do have several Cox and Norvel/AME engines however.

Good Luck - your persistence reminds me of when I was a kid trying to start some of my engines.

Dec 09, 2012, 10:46 PM
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PyroMan's Avatar
I will do my best not to use the E-starter again, but I can't promise anything

My fuel tank's fuel port was about 1/4" below the fuel intake port of the engine. I have attached some pictures of my testing setup. I will try lowering my tank like GliderJim suggested. I may also switch my tank out with a syringe without the plunger so I can see the fuel that's left.

I feel like the engine could've been flooded because I primed, pressureized the tank and filled up the venturi, and squirted fuel in the engine through the exhaust ports often. So I will do less of that next time.

I couldn't find anywhere on my starting fluid can that stated that it contains ether. I'm assuming it does because that's what I've always been told that starting fluid is. Now that I think about it, dad may have a can of better quality starting fluid in the shed. I'll check that out and see what it says.

I'm real anxious and excited to get this thing going! Just the few seconds I had today of it running at high rpms was cool. Especially how I could see the glow from the combustion through the exhaust ports!
Dec 09, 2012, 11:22 PM
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GliderJim's Avatar
Your setup looks pretty good to me. I don't know that I would raise the tank any, although a picture from the front would allow us to see the relative heights of the engine and tank a little better. Since you have nice clear fuel tubing, you should be able to see if there is any fuel in the line. You want a situation where you can fill the tank and not have the fuel run into the engine all by itself, which you should be able to see happening. If you prime and start the engine with the fuel line empty, then you should expect to see the fuel work it's way through the line as the engine runs off the prime. It might not make it all the way to the engine though, which means you would need to have some fuel in the line to start with. You can put your thumb over the venturi opening and turn the prop a couple of times to draw the fuel up into the tube. However, if the fuel just runs back down into the tank after you do that, that's no good either.
Last edited by GliderJim; Dec 09, 2012 at 11:23 PM. Reason: added last sentence.
Dec 09, 2012, 11:27 PM
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PyroMan's Avatar
The way I prime is by putting my finger over the venturi and turning the prop a few times to bring the fuel into the engine. Judging by your last post I'm assuming this isn't what you consider priming, so what Do you consider priming?

Also, I took multiple picture that showed the elevation of the fuel tank to the engine, but none came out good. The lighting wasn't working, the prop and spring housing got in the way and it was difficult to tell the height difference so I didn't post any of them.
Dec 09, 2012, 11:40 PM
Team Compass/KBDD Team Pilot
Ah Clem's Avatar
Priming is squirting a little fuel on the exhaust port.

Your set up looks good to me, also.

If it runs for a few seconds and dies after speeding up to a honk, it is too lean, or it is not drawing fuel (what Glider Jim was saying). You should be able to see the fuel in the line.
Dec 11, 2012, 11:13 AM
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PyroMan's Avatar
Yesterday morning was the last time I tried to get the engine running. I used the chicken stick for about 20 minutes with promising results. Although I never actually got it running, it would turn over on its own about a dozen revolutions and then stop. It did this very often. Maybe every other flip or so. While trying to start it today I had to continually stop, plug in glow starter to charge, and come back in 15minutes or so to try again. My glow starter is really old and doesn't hold a charge that good so I'm always having to deal with it dying. So when it died today and I plugged it in to charge, I went to find a better way to make my glow plug glow; something that would never die and will always be constant - a power supply.

I started out with small power supplies. I would rig them to my 1/2A glow clip and attach the clip to just the glow plug so I could see if it would make it glow or not. I would very quickly touch the center of the pole of the glow plug with my clip and then very quickly remove it. I did this to see if it would be too much for the glow plug to handle. If it didn't shine red hot instantly I repeated the process multiple times but each time leaving it connected slightly bit longer to see if it worked. I did this to two power supplies (one with more output than the other) and neither one would even make it glow a little, so I got my third sized power supply. It was just about half an amp more output than the biggest power supply I had already tried. I hooked it up and began my process. I connected the clip to the glow head and extremely quickly (probably less than 1/10 of a second) touch the center pole of the glow head and removed it. POOF! The glow plug's nichrome wire instantly vaporized in a flash of red-orange flame. I instantly knew I was screwed

I knew I couldn't repair it. I looked online to see if I could drill and tap the head for a regular glow plug but everywhere I read says that it messes up the size of the combustion chamber and it causes the engine to not run well. So I'm really upset. I'm mainly mad at myself for doing something I knew better than to try, but also upset that I screwed up something that's pretty hard to find.

I would order a new head off of eBay, but I don't have the money right now because I have spent most of my spending money on two new Cox .049 Sure Starts from someone from here on RCG. So those should fill my need for a 1/2a engine. I will put one of those on my first balsa scratchbuild that I plan to start sometime after Christmas. I wanted to use my McCoy for the plane, but right now that isn't an option.

I guess the only good thing that has come from this is that I won't be trying that again Everything's a learning experience I guess. . .
Dec 11, 2012, 12:06 PM
Registered User
Originally Posted by PyroMan
I connected the clip to the glow head and extremely quickly (probably less than 1/10 of a second) touch the center pole of the glow head and removed it. POOF! The glow plug's nichrome wire instantly vaporized in a flash of red-orange flame.

....... Everything's a learning experience I guess. . .
What you've learned is that you can't outrun electricity!!

The value you need to check is the voltage output. Most of the older plugs will handle 1.5 to 1.75 volts. Some will go a little higher, the older NORVEL plugs for example, but 1.7v or so should top you out.

Igniters using NiCd batteries will usually meter ~1.4v when fully charged, but will drop down when under load.
Dec 11, 2012, 01:01 PM
Registered Misuser
Vince77's Avatar
Dude... I've been there. I once hooked my glow plug clip to the starter terminals on my power panel by mistake... The starter terminals go straight to the 12 volt battery. I tried three glow heads before I realized my mistake.

The Cox battery box is two D cells in parallel, giving 1.5v at twice the current... Always worked a treat. If the glow head didn't glow too bright with the 1.4v that comes out of a NiCad glow driver, you probably needed a new head anyway.
Dec 11, 2012, 01:23 PM
Registered User
PyroMan's Avatar
The glow head glowed very bright when my Hot Shot 2 was fresh off the charger, but it died so quickly it got on my nerves. The glow starter is like 6-7 years old, but it has only been charged a maximum of 6 times before I started working on this engine.

I wasn't going to disclose the size of my power supply because it makes me look a little more stupid, but I will anyway. It was a 12VDC 1.5A powersupply In my defense though, I tried a 9v .5A and a 12v .7A power supply and neither one made it even glow. Which I found kinda strange, but then I just decided to ramp it up a little more, and, well, you see where that got me.
Dec 11, 2012, 03:20 PM
Registered Misuser
Vince77's Avatar
Sounds like the other power supplies ran out before they broke the 1.5 to 3 amps required to fully light a glow plug (max 3A at 1.5v = 4.5 watts). That last one though... 1.5A at 12v = 18 watts.

They're just like (exposed) light bulb filaments. Double the voltage and (if the power supply can handle it) you double the power.

But yea, we've all been there. Just learn from it and you'll be ahead for next time. Not like you did something really crazy like forget to add oil after an oil change... (I had to drive that guy to work for two months )
Dec 11, 2012, 04:58 PM
Team Compass/KBDD Team Pilot
Ah Clem's Avatar
"I wasn't going to disclose the size of my power supply because it makes me look a little more stupid,"

Never-not stupid at all-we all have to learn. I had to re-learn after staying away from Testors/Wen Mac .049s for 40 years or so. I had the same difficulties you are experiencing a few months ago, AND I USED TO DO DEMOS FOR TESTORS!


Glow plugs show up on Ebay for between $ 1 an $3. The engines themselves are very cheap, used. Mecoa makes a replacement head, similar to the one you were talking about making, to replace the stock head and be able to use a standard glow plug (oddly enough, like the earlier Wen Macs did).

The Testors/Wen Mac engines, with the right fuel, will start more easily than the Cox reed motors (which are also very good and reliable, by the way). We used to start two and three of the Testors motors like yours, simulateously (for simulated racing, dogfightts, and flying one in each hand). Also had to start two for the P-38, which was not a problem.

The dual port Cox motors do seem to have a bit more power, but the Testors/Wen Macs were more reliable-this is after running very many of both over the years.
Last edited by Ah Clem; Dec 11, 2012 at 05:04 PM.

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