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Old 06-24-2014, 08:26 AM
vmceachern is offline
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You can't fix STUPID
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Quote:
Originally Posted by Windecker View Post
Greetings experts!
I have a new to me, recently serviced 3W110iR2 inline engine that is doing a few funky things. It was set 1/4 turn rich by Aircraft Int. during service (approx. 1 1/4 out on highs, 1 out lows).
It was 4 cycling a LOT and not making good power. Running better at mid throttle and richer at full throttle. I leaned it carefully and repeated flight testing as it tends to richen in the air and not hold the settings from ground testing perfectly.
Here are the strange parts.
As the fuel tank empties in the plane, it runs better (sounds like it is leaning out).
As the plane is nosed down to gain airspeed for a maneuver it richens noticeably.
As the plane noses up it leans and sounds great.
ANY negative maneuver such as the roll at the top of an immelman causes the engine to basically die upon immediate negative (or lack of positive) g's. The top of a loop, while inverted in a roll...
I have re plumbed the tank and am positive the clunk is working normally. The vent is open and not restricted.
It has two independent ignition systems so a bad connection or whatever would have to affect both circuits.

I checked the needles after the last flight and found them almost to spec but a tick rich yet on the rear carb, a tic lean on the front carb.
I am going to route the vent from the carb base to inside the plane but beyond that think I have carb issues beyond tuning.
Thoughts?
Thanks
Windecker
Post some pics of the install. Sounds like airflow issues around the carb venturi to me. But hard to say without seeing the configuration.
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Old 06-24-2014, 08:59 AM
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Hi Windecker:

I had the same problem with the same engine in a CARF Spitfire. There were two issues. The fist is that if the engine is not mounted with the cylinders straight up and down (plugs at the bottom), the fuel collects behind the reed valve and when you do a maneuver it dumps into the cylinders and runs very rich for a while or quits. It would happen on take off rotate, rolls and loops. I fixed it by making a neoprene foam shape to go in the chamber behind the reed valve. To test I made a 2x4 stand and ran the engine. When you rolled to the left 90 deg. it would go rich. Rolling to the right had no problem. Pointing up would also go rich. When you roll right the fuel stays in the small chamber behind the read valve. Otherwise it dumps into the engine.

The second issue is that the needle valves would move in flight. I found that was happening at Top Gun two years ago, and someone said that I think your cowl is touching the needle valve and causing it to move. I cut a good amount of clearance around it and on my first flight the rear high speed needle valve came completely out somewhere in the field. I managed to finish my round on one cylinder. After that I locktighted the needle vales in and it has been great ever since. Gehart from AI recommended to shorten the needle valves, reduce vibration, and stretch the springs, but purple locktight (the light stuff) worked fantastic.

Good luck with yours
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Old 06-24-2014, 09:09 AM
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Here are a few photos
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Old 06-24-2014, 10:00 AM
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Thanks for the quick replies!
I have to say, the foam filler pad under the reed block makes a lot of sense, that sounds exactly like one of my issues. I can deal with it richening on the decent angles as long as it stays pulling through the arc on the top of the loop...
Where can I locate that material?

My engine is mounted at about 7 or 8 O-clock as viewed from the front, cylinders offset from vertical maybe 15-20 degrees, carbs offset the opposite, about 4 O-clock, offset in the other direction...

Pretty sure my needles are not moving as I was adjusting and watching them pretty closely, but I can add some loc tite easy enough to eliminate that as a concern.
Maybe the foam pad will also take care of it richening with the nose down. It seemed to go richer with higher throttle settings than with slightly lower settings.

I don't have any good pictures here to show the installation. I think some of the fluctuations in settings could be airflow, this cowl is mostly air in and not as much air out so I expect it to pressurize somewhat. I did try flying with the gear doors open increasing exit air but it had no apparent affect.
Thanks!
Windecker
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Old 06-24-2014, 10:34 AM
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Hi Windecker:

Mine was rotated 17 degrees to fit the cowl. I took lots of pictures and documented it for 3W but they acted as though it was totally unheard of. I proved it out with my stand beyond question.

I got the Oil Resistant Neoprene foam rubber from McMaster Car. Here is a link to the web page

http://www.mcmaster.com/#85175k65/=sjr59a

I got the smallest quantity they would sell which is 12" x 54" x 3/4". I shaped it on the band saw and belt sander. As you can imagine I have a lot left over. If you click on my name in the upper right hand corner you can send me a private message and i will send you some.

By the way I had cut some off and put it in a jar with gasoline. it sat for a week with no change. i had it on my work bench for months after that with no issue of the rubber getting soft or degrading from the fuel.
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Old 06-24-2014, 10:42 AM
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I just found the original post with the results of the test I did on the 2x4 frame. It is at:

https://www.flyinggiants.com/forums/...40#post1331136
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Old 06-24-2014, 11:49 AM
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Lou,
Thanks for the link, I am quite confident that your fix will correct my issue as well.
Turns out I had a block of Neoprene at the shop so I am covered for material, thanks or the kind offer.
I am excited at the prospect of such a simple fix so I can fly with confidence.
In reading the other thread you linked, find it concerning regarding putting a drain there back to the tank. Sounds like a good way to suck fuel right into the engine on exhaust stroke and pressurise the tank on intake strokes... Maybe I'm missing something.

Any idea where your needles wound up?
Thanks again!
Windecker
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Last edited by Windecker; 06-25-2014 at 05:06 AM. Reason: cell phone typos
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Old 06-24-2014, 01:05 PM
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I actually tried some thing that that and it was a disaster. I ran a 1/8" small tube from the bottom of that chamber out to a perry one way valve from both cylinders then to the tank. With each down stroke of the piston it would clear out the chamber of any excess fuel. What happened is that is pressurize the tank so much that it was shooting out the overflow when ever the fuel splashed on the top vent.

I also tried with some more success to take that line and with a 1/16 dia tube vent it back inside the carburetor inlet. That worked ok to fix the fuel dumping problem but most of the raw fuel ened up inside the cowl and I had a lot of excess 2 stoke oil all over the plane that did not evaporate. The best solution and what I am using now is with the neoprene foam. i flew in this years Top Gun with it and it flew great with out missing a beat.
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Old 06-29-2014, 05:34 PM
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Lou,
Well, no kidding, I duplicated your effort and the engine responded just like yours did! No more ill tuned operations in general and no more quitting during non positively loaded maneuvers.
It was not changing tune from ground to air any longer and ran like it should.
Thanks very much for the tip!
I can climb, dive, roll, whatever and it just stays in tune, excellent. Wish 3W would respond to this and correct the issue.
Thanks again.
Windecker
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Old 06-29-2014, 09:38 PM
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Hi Windeker:

I am glad someone else was able to make use of my efforts. I thought I was going crazy for a while but what kept me going was that so many people had no issues at all. But if you tilt it the right way watch out.

Happy flying.
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Old 07-11-2014, 04:55 PM
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clairify a few points

I was hoping I could get a better picture of a few points in the very first post. I apologize if this has already been covered.
When referring to the metering valve adjustment the statement:
" For general purposes, the lever will be almost perfectly parallel to the carb base."
- Is this with the lever in its natural position, spring pressure pushing up on the back of the lever which us in turn pushing the valve down in its seat or with a little down pressure applied to the back of the lever lifting the front 'fork' up to contact the valve? (if I am reading too much into it please say so)


Secondly when considering this advise:
"A very common problem with cowled in engines is, the air pressure in flight changes the "natural" pressure on the float diaphragm... solder a piece of brass tubing where the vent is, and route the vent line to a better location."
- How long should this vent line be, how far back in the fuse should it go? Would the end of the line be left open or would something go on the end of it to further minimize pressure variance from airflow?


For those of you wondering why I am asking it is because I can get a great tune on the ground, runs smooth, idles well, transitions well, starts easy and is very responsive to throttle but in the air it gurgles like it is getting rich. this is straight and level, inverted, upline .. .anytime I have reasonable power applied. I do make good power and it has never dies on me but the gurgling in bothering me and I have to imagine I could get better power.


FYI I have an RCGF 50 swinging a zoar 21x10 prop on 87 octane eth free with echo synthetic blend oil at 32:1. I also tried 93 octane gas with redline and lucas ethanol stabilizer (not sure the exact mixture) with the same results


I have tried:
- with and without a velocity stack (currently with)
- about 2' of tygon fuel line running into the fuse from the vent as described above, open on the end
- I have put fresh gaskets and diaphragm on the carb
- fresh fuel lines
- engine has new crank and rod (had a bad bearing)
- new bowman ring with about a gal, gal.5
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Old 07-17-2014, 09:12 PM
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Hey guys, I'm running a DLE 35 and when I chop the throttle it dies or almost dies, but when I ease back on the throttle it will idle just fine. If I up my idle speed than it starts to idling high. I am wondering whats wrong is it to lean on the low end or what is going on with such erratic idle speed. Any help would be much appreciated.
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Old 07-17-2014, 11:24 PM
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Quote:
Originally Posted by ericrs View Post
Hey guys, I'm running a DLE 35 and when I chop the throttle it dies or almost dies, but when I ease back on the throttle it will idle just fine. If I up my idle speed than it starts to idling high. I am wondering whats wrong is it to lean on the low end or what is going on with such erratic idle speed. Any help would be much appreciated.
probably too rich on the low end...try leaning the low end and see what happens. btw i have found a few servos that will over travel for a split second before coming to position... check that too.
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Old 07-17-2014, 11:28 PM
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Ok I will try that and see if it works. Thanks!
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Old 08-01-2014, 04:32 PM
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I am buying an airplane from a guy who runs 64:1 with Redline on a DLE-170. I want to run 40:1 with Stihl HP Ultra. Will I need to reajust the needles for the added oil in the 40:1 ratio? Thanks in advance, JC
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