Same with those I've been around. I always suggest taking them off.

I've woundered about taking off the needle 'blocker'...I feel better about giving it a try! spial-72 helped in the descission

Done! Thanks to all for the info.

Enjoyed your note on working with the .61 Evelotion...I have a friend who does mechanical work and annuals on full sized planes. I'm trying to costantly fly a J-3 cub...the .61 was way over powering the plane, switched to a O.S. .46 with a 3 bladed prop...much better control, especially with the tork problems and engine performance. He listens to my sad stories on engine performance, tips rolls. 3D's, and underperforming rudder servo tork on take-offs with my cub. He has helped a lot with suggestions on tank location, engine venting, running rich and lean and a good lecture on tork. I guess the mechanics of flying R/C vs. the full scale is... we are just smaller.

Ditto, thanks guys for all the help. She at least runs properly now. I can take the fine tuning from here.

Last question for now: How do you tell what glow plugs are? Can you tell by looking at it? The plug I started with and the OS #8 and the Tower Power plug all look the same to me. Is it the electrode (term?) length inside the plug? As far as I can tell the threaded barrels are the same length.

The best way to learn about glow plugs is to experience them.

The Tower Power is very much like the OS two stoke plugs. They must be made by OS?

In the four stroke plugs the OS "F" and the Saito "SS" and the Y-S four stroke plug all look about the same. They run about the same also.

The standards of the industry right now are the OS "8" and OS "F". Other plugs are usually compared to them

An update for those interested:

My tuning has evolved:

I now run Omega 15%. A buddy recommended the synthetic version, but the Omega was recommended earlier. I also finally got the bright idea to call customer service. They recommended the Omega.

The OS#8 plug run ok, I guess. Much better than when I started this mess. I tried a 4 stroke plug, a H9 "super plug" supposedly OEM for this engine. The 4 stroke plug cleaned up the engine performance quite a bit IF I can get the engine running in the proper direction. With the OS#8 it starts backward about 25% of the time, with the 4 stroke plug about 50%. From my research and advice this is an indication of too hot a plug - causes detonation (preignition) and she starts and runs backward. I'm not too sure what to do about this yet. It runs like crap with a cooler plug and barely at all with the 10% (cooler?) fuel.

Anyways, what I have now is an engine that runs quite well, with LOTS of power IF it doesn't start backward AND I can get it warmed up.

It still appears to be very running rich (visually) although tuning says it's just right.

It is very difficult to keep the engine temp up. The air is getting quite cool now. I've never run an engine in the winter time (actually this is my first year with glow) but if I pull the engine to idle with an extended glide, for example landing, the engine seems to cool enough that it'll spit and die on the transition back up (like a touch and go.) If I fly it and have fun, or even just putter around the skies, it acts pretty good.

The low speed needle is secured from vibrating-loosing adjustment by an o-ring I installed around the needle. Works well.
The high speed is secured by a piece of fuel line slipped over the knob. Works well.

Is the ambient temps too cool? Could I install a shield in front to limit the amount of air over the engine and keep the temps up? Y'know like they do on big diesel trucks in front of the radiator up north?

Any takers?

The spitting and dying out is an indication of either the low speed being set too rich, and/or a cold plug. Considering your location, I wouldn't worry about the temperature at all.

Hmmmm. I expect my plug is not too cold. Actually the H9 (OS #F) it's supposed to be quite hot for a 2 stroke.

It was 40-50F that day.... Not too cold, but I didn't know how it would effect the engine. At least I can rule that out. Thank you.

...still plugging away. I guess I'll follow someone else's recommendation and pull the carb and needle sets apart for a good cleaning.

Pull the lines off the carb, pull the needle assy (count the turns) and use compressed air to blow
every which way thru all the open orfices. Re-assy.

I use the H9 plug in all mine Evo's and have never had a problem. I live in the same climate
you do. Don't worry about it being too cold. If it's that cold, got no business going.

Keep us posted.

Well I pulled the carb completely apart. It's pretty simple actually. I knew as soon as I had all the pieces laid out that dirt/sludge/dried oil was not the problem, but I washed everything in my parts washer anyway. I blew all pieces out and noted any passages taking special care to make sure they were unobstructed and undamaged.

I have to start it yet. Why does it rain on every weekend that I have some flying time?

I'll keep ya posted.

Spiral 72,

Could you take a quick look at the following thread and see if it might apply to your situation?
http://www.rcuniverse.com/forum/fb.asp?m=6829281

Thanks,
Doug

Back flushing the remote needle valve sometimes helps if there is debris in there. I flush glow fuel thru a coffee filter to see it.

Outside air temps probably have nothing to do with how your engine runs. I suggest at least trying an A3 plug and seeing if that turns it into a better running engine.

That is very interesting. While I wouldn't describe the mess out of the muffler as grey goo, it is dark-ish with some viscosity. I haven't flown in near that cold, maybe 45 F at the coldest.... (that's on the ground, dunno what the temp is 300ft altitude) I WILL check into this. Actually if it's true that might be why my tuning changes so much between days and between flights.

For all still interested:

I had an amazing thing happen. New Years day, a buddy and I put the plane on a stand and tuned it at the house. The engine ran marginally well as I am used to.... much improved over when I started this drama. We loaded the planes and the gear and went to the field. Temp was about 55 F.

We unloaded, assembled and he put his in the air. I started mine, it run ok, but I choked the engine before it warmed up and died. I tried to restart - nothing. After about 2 hours of fooling with the thing and methodically tuning, trying to stay within the previous needle setting, checking fuel tank lines, blowing through the lines etc, etc, etc. I wasn't moving fuel. I'd prime the engine by dripping fuel in the carb..... run, stop..... run, stop. Several guys come over, blah, blah, blah. I finally removed the LS stops and opened the needle one full turn! Blam fired up and run better than it ever had. What's up with that!?

I'm not an idiot (arguably), maybe inexperienced. I've tried to tune this thing very methodically by ear and with the pich test all over the needle settings and the stupid thing run marginally well at the settings I had, then not at all.

Anyways, it runs pretty good now. It still dumps a lot of fuel out of the muffler but it's making power like a .61 should. The transistion is pretty good, it's a little cold natured but nothing I can't handle.

Several posts up I removed the carb and cleaned very thoroghly(SP?) and I've had the engine running several times since then. The tuning was the same before and after the cleaning.

I'm still gonna play with it. And I will check the fuel delivery/pressure line blockage thing mentioned. Thanks for the link btw.

Either your muffler pressure nipple is clogged, your fuel tank vent line is not permitting enough air to enter the fuel tank as the fuel burns off (check for crimps), or the fuel is bubbling in the fuel tank when the engine is running and is causing the mixture to go lean. It could be something else, but I would check for these things first.


Ed Cregger

Thank you. I've checked all that except the muffler nipple. But I will add it all to my list of "stuff to check"

is it possible for you to post photos of the engine, airframe, and the tank installation ? That might help a great deal.

Bob

Sure, that's not a problem. I'll try to get them on here tomorrow morning.

Here's the airframe.... I'll get the rest tomorrow.

Here's the pictures as requested:

pic #2 shows the fuel lines running behind the engine and through the firewall. If I disconnect the lines from the engine they slide in and out through the firewall easily... So, they're not kinked or pinched in any way.

pic #4 is my feable attempt to show the relationship between the fuel tank and the engine. I think the stopper and lines are about 1/4" lower than the HS needle. That'd put the clunk about 3/4" below the HS needle.

pic #6 is the lines through the firewall. I cut that access door in the bottom of the fuselage. I braced it up so it would be just as strong before I removed the sheeting.

pic #7 is the rear of the tank in the fuselage

The fuel tank is mounted sideways (if there is such a thing) and the clunk moves freely to all four sides of the tank.

Thanks for the photos....

Before I say anything on the aircraft... engine trouble shooting rule #1
Remove the engine from the plane. Put it in on a decent test stand.

(you are an experienced modeler and may already practice this, but for the benfit of others reading...)

Controlled conditions - easy to see - easy to adjust - easy to make changes. Generally is more sold and stable than the airplane installation.
Run the engine. Keep it configured at first as it was in the plane. Same prop, spinner.
If it still misbahaves, check and change what is possible. Prop - plug - fuel. Change one thing at a time.
If it runs properly on the test stand, you have just isolated the problem - and the fault lies somewhere in the airframe/fuel system.

Something to consider based on seeing these, it was not clear entirely, but it looked like the tank is a fairly tight fit in there.

You should isolate the fuel tank from the airframe. Rubber padding all around.

Although you noted that you did not see bubbles in the fuel line while testing on the ground, it is not impossible that, in flight, the harmonics can cause the fuel to agitate and create foam in the tank. Once foam appears, the engine will go lean, and there is no two ways about it. Once those little temperature spikes hit the engine.... it is just not going to run right.

In my experience trouble shooting engine issues, over 90% of reported problems were traced back to the fuel system. So that is usually the first place I recommend that folks look. To this point, you have obviously followed that fault path per your photos and descriptions... as you have specifically check many elements in the fuel system.

That might not entirely be the problem, but it is good practice to isolate the fuel tank.

One thing I would do first --- remove the exhaust extension. See if that makes a difference. Sometimes, under the right conditions, the extension can act as an inadverting tuning device as it hits a certain frequency (rpm). This can cause surging. Yeah, its a long shot, but by far the easiest thing to try first.

Second easier thing to try, or at least worth an experiement.... change to a different prop. Unload the engine a bit and see if it happier. Two blade 11x7 would be a good start, then perhaps try a 2 bladed 12x6. A bit less load, and the engine will respond differently to each prop as it settles into an rpm range.

Let me leave it at that.... let me know how you make out.

Bob

Thanks for the great reply.

It might take me a couple days to pull the engine and make a stand for it and dedicate a couple hours to it, but I will, just as you recommend.

I really don't think there's anything mechanically wrong with the engine.... Why? Ummmm, I dunno. It just runs so smooth, sometimes.... Ok rarely, but sometimes.

Maybe I've put so much time in this thing that, running it on a stand is exactly what I need.

I'll check on RCU, but what level should the tank be? Stopper in line with the HS needle? Cluck in line with the needle? What do you recommend? Not that there's anything I can do about the tank, you are right. It fits tight. I expressed a concern about no foam between the tank and the frame, but the guys at the field said don't worry about it. And they had the planes to prove it. So I haven't. There's no wood I can cut out for foam unfortunately. Maybe I can run a smaller tank. I think I have an 8oz at the house.

One thing that has always bugged me though. The engine seems to dump a ton of raw fuel out of the exhaust even when it acts like it's running lean. It's happened on all the fuel types I've run though it (maybe except a full synthetic 15%, I'm not sure)

Maybe it's just the angles of the photos, but it looks like your fuel tank is mounted too low. The top-side of your tank appears almost level with the center of the carburetor inlet.
In a desired arrangement with the airplane sitting level, the center of the carburetor inlet would be ~1/4 inch above the centerline of the tank. With a 12 oz., side-mounted Dubro tank, the tank centerline would be ~1-1/4 inch below the top-side of the tank. The desired arrangement would have the top-side of the tank ~1 inch above the carburetor inlet .

There is some validity to keeping in mind the tank location. You do want the tank in decent proximity to the engine/carb/crankshaft.

But also consider, that the tank "location" only exists for straight-n-level flight. So the engine has to be tolerant of drawing fuel uphill, downhill, and under g-load conditions. Example would be, consider where your clunk location is when climbing out on takeoff at ... say .... 20 deg nose up. Most engines run fine like this.

On my own test stand, the the tank CL ends up mounting about 1/2" below the spraybar in the carb. At full fuel, the fuel level is above the carb, and obviously as fuel runs out, it has to go up hill a bit. At low fuel conditions, that results in about a 1.5" below-carb fuel level. I have not run across an engine that did not run through a full tank.

My point here, the tank position is something to consider, but its probably not causing the surging.

About the raw-fuel dump...

If its obviously spraying raw fuel in the exhaust, and still acting as if it is hot/lean or really sags off ---- it may be overly restricted on the exhaust.

Let me know how the test bench runs go.
Bob

(For reference - an image attached shows the layout of Dub's test bench. Mine is simlar, just a little smaller. Yeah, it is elaborate by most standards, but it has the basic components. You can see here there is no tremendous attention to fuel tank location. Focus is on safety as well as easy setup, measurements and adjustments)

The weekend didn't work in foavor of the airplane. I had a job to finish by Monday (which didn't get completed, AAAHH!)

I found some 3/4" ply I'm gonna bolt the engine and related stuff to, and c-clamp it to my workbench in the garage. I was going to use MDF but then I remebered what MDF does when it comes in contact with anything liquid. Ply it is.

I'll keep you informed asap.