Fuel line pinch test
12-21-2011, 05:19 PM
#76
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RE: Fuel line pinch test
ORIGINAL: Firepower R/C
rudder turns,
Hmm, I have never heard of pinching the muffler line before. Very interesting... it seems logical. I will try that next time I run an engine. Your low end technique is good, and is how I did it before learning the pinch. I guess I am too impatient sometimes, heh heh.
In response to billd76, yes, I do pinch the tubing while at idle, then listen to what it does. If it dies really quick-too lean. If it slowly revs up over 5-15 seconds and then dies- too rich. If it speeds up slightly then dies in a 2-3 seconds- just right. Works great for me, given all other things are solid in the installation. Each engine will vary slightly in the times as well. This technique really helped all of my Evolution engines perform excellent. Oh, and my Hangar 9 Corsair has a Super Tigre 90 in it, and is the most well behaved engine I have ever owned. Never ever a deadstick. Pinch test-adjusted. Just my preference, however.
LONG LIVE THE GLOW ENGINE!!!
Now why do I hear only crickets?
rudder turns,
Hmm, I have never heard of pinching the muffler line before. Very interesting... it seems logical. I will try that next time I run an engine. Your low end technique is good, and is how I did it before learning the pinch. I guess I am too impatient sometimes, heh heh.
In response to billd76, yes, I do pinch the tubing while at idle, then listen to what it does. If it dies really quick-too lean. If it slowly revs up over 5-15 seconds and then dies- too rich. If it speeds up slightly then dies in a 2-3 seconds- just right. Works great for me, given all other things are solid in the installation. Each engine will vary slightly in the times as well. This technique really helped all of my Evolution engines perform excellent. Oh, and my Hangar 9 Corsair has a Super Tigre 90 in it, and is the most well behaved engine I have ever owned. Never ever a deadstick. Pinch test-adjusted. Just my preference, however.
LONG LIVE THE GLOW ENGINE!!!
Now why do I hear only crickets?
12-21-2011, 06:16 PM
#77
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RE: Fuel line pinch test
Bill
On that super tigre you have to be sure the spray bar slot is in the right orientation, otherwise big headache. Somewhere there is a thread explaining how to set the spray bar.
On that super tigre you have to be sure the spray bar slot is in the right orientation, otherwise big headache. Somewhere there is a thread explaining how to set the spray bar.
12-21-2011, 07:50 PM
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RE: Fuel line pinch test
ORIGINAL: goirish
Bill
On that super tigre you have to be sure the spray bar slot is in the right orientation, otherwise big headache. Somewhere there is a thread explaining how to set the spray bar.
Bill
On that super tigre you have to be sure the spray bar slot is in the right orientation, otherwise big headache. Somewhere there is a thread explaining how to set the spray bar.
Thanks,
12-21-2011, 08:37 PM
#79
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RE: Fuel line pinch test
Bill, a 16x7 prop is just too big a load for the ST 90 engine. Drop down to a 13x6 or 14x5 and the engine will be much happier.
Since this thread has turned into a clearing center for poor engine performance, one area that should be addressed is overloading the engine with too big a prop. In recent years, manufacturers of engines have started calling out larger and larger props in their engine guides. Strange thing is that physics of internal combustion engines have stayed the same. I suspect they do this for two reasons:
1.) Call out a bigger prop than your competitor does, and you must have the stronger engine.
Well, if you examine the data, the peak power occurs about 4 to 6 thousand RPM higher than what you will ever see with that oversized prop. For a 2C engine, that uses an ordinary muffler, you want to have a ground RPM that is 2 to 3 thousand below the peak power. In the air, the engine will unload about 1500 RPM give or take depending on how clean aerodynamically your plane is and you will achieve the rated power.
2.) Makes them run very quietly - Mostly because it is not making any power. But important in some very restrictive areas.
Now how can you tell if your airplane's engine is over-propped? RPM is a good guide if you have a tach, but if you don't then it's time to get to know your engine. An engine that is over loaded will have a very narrow needle range on the high speed needle valve. In other words, it will go from 4 cycle rich to lean with not much adjustment of the needle valve.
Put a much smaller, lighter prop on, and suddenly the needle becomes much broader, and the engine will not be so critical on the setting.
Since this thread has turned into a clearing center for poor engine performance, one area that should be addressed is overloading the engine with too big a prop. In recent years, manufacturers of engines have started calling out larger and larger props in their engine guides. Strange thing is that physics of internal combustion engines have stayed the same. I suspect they do this for two reasons:
1.) Call out a bigger prop than your competitor does, and you must have the stronger engine.
Well, if you examine the data, the peak power occurs about 4 to 6 thousand RPM higher than what you will ever see with that oversized prop. For a 2C engine, that uses an ordinary muffler, you want to have a ground RPM that is 2 to 3 thousand below the peak power. In the air, the engine will unload about 1500 RPM give or take depending on how clean aerodynamically your plane is and you will achieve the rated power.
2.) Makes them run very quietly - Mostly because it is not making any power. But important in some very restrictive areas.
Now how can you tell if your airplane's engine is over-propped? RPM is a good guide if you have a tach, but if you don't then it's time to get to know your engine. An engine that is over loaded will have a very narrow needle range on the high speed needle valve. In other words, it will go from 4 cycle rich to lean with not much adjustment of the needle valve.
Put a much smaller, lighter prop on, and suddenly the needle becomes much broader, and the engine will not be so critical on the setting.
12-21-2011, 08:38 PM
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RE: Fuel line pinch test
billd76,
I would say that your installed prop is too much load for that engine, that is, if your carb isn't bad, or one of those oddball .40-size ones they stuck on right before the operation moved to China. In my opinion it might run with that prop, but it won't run like it should. I currently have a Master Airscrew 14X8 on mine, and don't want to load it up any more than it is. I also have never used an Xoar prop, but have heard from a friend that does use them that they "bite" harder than most other props of a similar size. He says they are great props, so I guess I need to try one! Also, do you also have the stock muffler or an otherwise large-volume muffler on it? There are a few smaller aftermarket ones that choke the engine, which would aggrevate the whole larger prop thing even further.
I would suggest trying a smaller prop, and then adjusting the carb using the pinch method on both needles and come back here and post your results... deal?
Good luck!
EDIT: Oops, High Plains beat me to it... heh heh. He hit the nail on the head!
I would say that your installed prop is too much load for that engine, that is, if your carb isn't bad, or one of those oddball .40-size ones they stuck on right before the operation moved to China. In my opinion it might run with that prop, but it won't run like it should. I currently have a Master Airscrew 14X8 on mine, and don't want to load it up any more than it is. I also have never used an Xoar prop, but have heard from a friend that does use them that they "bite" harder than most other props of a similar size. He says they are great props, so I guess I need to try one! Also, do you also have the stock muffler or an otherwise large-volume muffler on it? There are a few smaller aftermarket ones that choke the engine, which would aggrevate the whole larger prop thing even further.
I would suggest trying a smaller prop, and then adjusting the carb using the pinch method on both needles and come back here and post your results... deal?
Good luck!
EDIT: Oops, High Plains beat me to it... heh heh. He hit the nail on the head!
12-21-2011, 10:43 PM
#81
My Feedback: (15)
RE: Fuel line pinch test
ORIGINAL: rudder turns
..or your clunk is too far back in the tank,it should be a 1/4'' at the closet to the back of the tank,so the engine doesn't starve on take of or maneuvers...
..or your clunk is too far back in the tank,it should be a 1/4'' at the closet to the back of the tank,so the engine doesn't starve on take of or maneuvers...
Kurt
12-21-2011, 10:53 PM
#82
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RE: Fuel line pinch test
It's that pesky acceleration Kurt, it pushes the clunk back and stretches the clunk line. One must also allow that clunk fuel line seems to grow slightly when exposed to fuel for long periods. I actually encountered this phenomena a couple years ago in a beginners plane. So leaving a gap of 1/4" from the clunk to the rear of the tank is a good idea. Some suggest even filing a notch in the clunk, but I think that is overkill.
12-22-2011, 03:01 AM
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RE: Fuel line pinch test
Hi!
16x7 is way way to big prop!
If you fly at sea level the most suitable prop seizes are 13x8, 14x6 or 15x4 (even 15x6 or 16x4W APC in some occations/planes) . As usuall APC,RAM or Graupner Cam-Prop are the best props!
16x7 is way way to big prop!
If you fly at sea level the most suitable prop seizes are 13x8, 14x6 or 15x4 (even 15x6 or 16x4W APC in some occations/planes) . As usuall APC,RAM or Graupner Cam-Prop are the best props!
12-22-2011, 04:24 AM
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RE: Fuel line pinch test
ORIGINAL: jaka
Hi!
16x7 is way way to big prop!
If you fly at sea level the most suitable prop seizes are 13x8, 14x6 or 15x4 (even 15x6 or 16x4W APC in some occations/planes) . As usuall APC,RAM or Graupner Cam-Prop are the best props!
Hi!
16x7 is way way to big prop!
If you fly at sea level the most suitable prop seizes are 13x8, 14x6 or 15x4 (even 15x6 or 16x4W APC in some occations/planes) . As usuall APC,RAM or Graupner Cam-Prop are the best props!
12-22-2011, 06:43 AM
#85
RE: Fuel line pinch test
Someboby pinch me, I must be dreaming that a thread about pinching has gone on for 4 pages!
Tune the high until it runs, tune the low until it transitions. Done! Now go fly! Remember, you can tune a piano, but you can't tuna fish
Tune the high until it runs, tune the low until it transitions. Done! Now go fly! Remember, you can tune a piano, but you can't tuna fish
12-22-2011, 06:55 AM
#87
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RE: Fuel line pinch test
My old ST 75 ran well at 12,000 RPM turning a 13x5 Rev-Up prop. It also turned about the same with a 12x6, but had much better climb with the 13x5. I generally like to have enough speed to do decent knife edge flight, then go for the largest diameter prop with lowest pitch that will achieve enough speed. This gives the ability to have unlimited vertical, whereas a smaller diameter prop with more pitch will fly faster, but usually runs out of steam after a few hundred feet.
Both the ST 75 and ST90 produce peak power at about the same RPM, with the 90 at a couple hundred RPM less. So I would target a peak RPM in the 11,550 range +/- 500. You always want to experiment with props with any new engine and airplane until you find which size works best. With experience you find one that you like best after 5 or 6 props, then stick with that size if possible because trim of the airplane is somewhat prop dependent.
Generally at this point if the airframe is straight and has the correct decalage, most of the final trimming depends on balance and thrust. Once you begin to appreciate how all of this works, then you will enjoy aircraft that fly better and are easier to land.
One final point - some airframe/engine combination will resonate badly at some RPM, usually you will hear a strange buzzing coming from the wing. When that occurs, try a slightly different size prop to move to another RPM.
Both the ST 75 and ST90 produce peak power at about the same RPM, with the 90 at a couple hundred RPM less. So I would target a peak RPM in the 11,550 range +/- 500. You always want to experiment with props with any new engine and airplane until you find which size works best. With experience you find one that you like best after 5 or 6 props, then stick with that size if possible because trim of the airplane is somewhat prop dependent.
Generally at this point if the airframe is straight and has the correct decalage, most of the final trimming depends on balance and thrust. Once you begin to appreciate how all of this works, then you will enjoy aircraft that fly better and are easier to land.
One final point - some airframe/engine combination will resonate badly at some RPM, usually you will hear a strange buzzing coming from the wing. When that occurs, try a slightly different size prop to move to another RPM.
12-22-2011, 07:16 AM
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RE: Fuel line pinch test
ORIGINAL: billd76
Yeah checked it long ago, it is where it should be. Hows the soon to be Marine doing?
Thanks,
ORIGINAL: goirish
Bill
On that super tigre you have to be sure the spray bar slot is in the right orientation, otherwise big headache. Somewhere there is a thread explaining how to set the spray bar.
Bill
On that super tigre you have to be sure the spray bar slot is in the right orientation, otherwise big headache. Somewhere there is a thread explaining how to set the spray bar.
Thanks,
12-22-2011, 08:27 AM
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RE: Fuel line pinch test
ORIGINAL: goirish
We head to San Diego next month. Ya don't think I will be a proud grandpa do ya?
ORIGINAL: billd76
Yeah checked it long ago, it is where it should be. Hows the soon to be Marine doing?
Thanks,
ORIGINAL: goirish
Bill
On that super tigre you have to be sure the spray bar slot is in the right orientation, otherwise big headache. Somewhere there is a thread explaining how to set the spray bar.
Bill
On that super tigre you have to be sure the spray bar slot is in the right orientation, otherwise big headache. Somewhere there is a thread explaining how to set the spray bar.
Thanks,
12-22-2011, 10:47 AM
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RE: Fuel line pinch test
ORIGINAL: Firepower R/C
billd76,
I would say that your installed prop is too much load for that engine, that is, if your carb isn't bad, or one of those oddball .40-size ones they stuck on right before the operation moved to China. In my opinion it might run with that prop, but it won't run like it should. I currently have a Master Airscrew 14X8 on mine, and don't want to load it up any more than it is. I also have never used an Xoar prop, but have heard from a friend that does use them that they ''bite'' harder than most other props of a similar size. He says they are great props, so I guess I need to try one! Also, do you also have the stock muffler or an otherwise large-volume muffler on it? There are a few smaller aftermarket ones that choke the engine, which would aggrevate the whole larger prop thing even further.
I would suggest trying a smaller prop, and then adjusting the carb using the pinch method on both needles and come back here and post your results... deal?
Good luck!
EDIT: Oops, High Plains beat me to it... heh heh. He hit the nail on the head!
billd76,
I would say that your installed prop is too much load for that engine, that is, if your carb isn't bad, or one of those oddball .40-size ones they stuck on right before the operation moved to China. In my opinion it might run with that prop, but it won't run like it should. I currently have a Master Airscrew 14X8 on mine, and don't want to load it up any more than it is. I also have never used an Xoar prop, but have heard from a friend that does use them that they ''bite'' harder than most other props of a similar size. He says they are great props, so I guess I need to try one! Also, do you also have the stock muffler or an otherwise large-volume muffler on it? There are a few smaller aftermarket ones that choke the engine, which would aggrevate the whole larger prop thing even further.
I would suggest trying a smaller prop, and then adjusting the carb using the pinch method on both needles and come back here and post your results... deal?
Good luck!
EDIT: Oops, High Plains beat me to it... heh heh. He hit the nail on the head!
going to check the clunk too, but last time I checked it was fine. Thanks
12-22-2011, 11:46 AM
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RE: Fuel line pinch test
ORIGINAL: HighPlains
It's that pesky acceleration Kurt, it pushes the clunk back and stretches the clunk line. One must also allow that clunk fuel line seems to grow slightly when exposed to fuel for long periods. I actually encountered this phenomena a couple years ago in a beginners plane. So leaving a gap of 1/4'' from the clunk to the rear of the tank is a good idea. Some suggest even filing a notch in the clunk, but I think that is overkill.
It's that pesky acceleration Kurt, it pushes the clunk back and stretches the clunk line. One must also allow that clunk fuel line seems to grow slightly when exposed to fuel for long periods. I actually encountered this phenomena a couple years ago in a beginners plane. So leaving a gap of 1/4'' from the clunk to the rear of the tank is a good idea. Some suggest even filing a notch in the clunk, but I think that is overkill.
I too learned this the hard way with a plane that kept displaying strange engine behaviour during acceleration and some manouvers.
Even thicker fuel lines WILL stretch enough to plug the clunk holes, even when those clunks have a notch in them.
I've also had people insist that they've left enough space to prevent this, only to discover they have the same problem.
1/4" is about right.
12-22-2011, 11:53 AM
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RE: Fuel line pinch test
ORIGINAL: billd76
Ok, first of all I beleive the pinch test is the easiest way for me to tune. I've read a couple of replies here that say you use it for the LSN adjustment. I get that, but do you pinch the line with the engine at idle for the LSN adjustment? For me the hardest thing to adjust is the low end. One other thing I haven't seen mentioned is that when you make a HSN adjustment, you sometimes have to readjust the LSN again as well. I have always had trouble tuning anything but an OS engine. Super Tigres are the worst, all the ones I've owned required adjusting everytime I go to the field. But the LSN is the one for me, that is hard to get just right.
Ok, first of all I beleive the pinch test is the easiest way for me to tune. I've read a couple of replies here that say you use it for the LSN adjustment. I get that, but do you pinch the line with the engine at idle for the LSN adjustment? For me the hardest thing to adjust is the low end. One other thing I haven't seen mentioned is that when you make a HSN adjustment, you sometimes have to readjust the LSN again as well. I have always had trouble tuning anything but an OS engine. Super Tigres are the worst, all the ones I've owned required adjusting everytime I go to the field. But the LSN is the one for me, that is hard to get just right.
There should only be a very slight drop in RPM's when the ignitor is removed.
12-22-2011, 11:58 AM
#93
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RE: Fuel line pinch test
ORIGINAL: opjose
Excellent advice.
I too learned this the hard way with a plane that kept displaying strange engine behaviour during acceleration and some manouvers.
Even thicker fuel lines WILL stretch enough to plug the clunk holes, even when those clunks have a notch in them.
I've also had people insist that they've left enough space to prevent this, only to discover they have the same problem.
1/4'' is about right.
ORIGINAL: HighPlains
It's that pesky acceleration Kurt, it pushes the clunk back and stretches the clunk line. One must also allow that clunk fuel line seems to grow slightly when exposed to fuel for long periods. I actually encountered this phenomena a couple years ago in a beginners plane. So leaving a gap of 1/4'' from the clunk to the rear of the tank is a good idea. Some suggest even filing a notch in the clunk, but I think that is overkill.
It's that pesky acceleration Kurt, it pushes the clunk back and stretches the clunk line. One must also allow that clunk fuel line seems to grow slightly when exposed to fuel for long periods. I actually encountered this phenomena a couple years ago in a beginners plane. So leaving a gap of 1/4'' from the clunk to the rear of the tank is a good idea. Some suggest even filing a notch in the clunk, but I think that is overkill.
I too learned this the hard way with a plane that kept displaying strange engine behaviour during acceleration and some manouvers.
Even thicker fuel lines WILL stretch enough to plug the clunk holes, even when those clunks have a notch in them.
I've also had people insist that they've left enough space to prevent this, only to discover they have the same problem.
1/4'' is about right.
I'm still doubting this much stretch and the fact that it will plug the clunk hole.[8D]
12-22-2011, 12:04 PM
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RE: Fuel line pinch test
ORIGINAL: Bozarth
But wait, pinching the fuel line does simulate what the engine will experience when climbing - reduced fuel flow. When the plane is held nose high, the effective distance between the carb and the clunk is increased, and with most suction feed carbs, the fuel flow is reduced.
But wait, pinching the fuel line does simulate what the engine will experience when climbing - reduced fuel flow. When the plane is held nose high, the effective distance between the carb and the clunk is increased, and with most suction feed carbs, the fuel flow is reduced.
12-22-2011, 12:40 PM
#95
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RE: Fuel line pinch test
ORIGINAL: grimbeaver
Personally if physically possible I would rather just hold the plane vertical then ''simulate'' climbing. Nothing is better then the real thing right? Lol.
ORIGINAL: Bozarth
But wait, pinching the fuel line does simulate what the engine will experience when climbing - reduced fuel flow. When the plane is held nose high, the effective distance between the carb and the clunk is increased, and with most suction feed carbs, the fuel flow is reduced.
But wait, pinching the fuel line does simulate what the engine will experience when climbing - reduced fuel flow. When the plane is held nose high, the effective distance between the carb and the clunk is increased, and with most suction feed carbs, the fuel flow is reduced.
I have never enjoyed picking up a .60 sized (or even a tiny .40) plane with the engine screaming at full throttle and pointing it skyward. The prop always seems way too close to my pretty face (No comments Bob) since my stubby arms aren't much longer than the prop. I have yet to figure out a way to feel anything but awkward (i.e. unsafe) doing so.
Kurt
12-22-2011, 12:51 PM
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RE: Fuel line pinch test
ORIGINAL: Bozarth
I have never enjoyed picking up a .60 sized (or even a tiny .40) plane with the engine screaming at full throttle and pointing it skyward. The prop always seems way too close to my pretty face (No comments Bob) since my stubby arms aren't much longer than the prop. I have yet to figure out a way to feel anything but awkward (i.e. unsafe) doing so.
Kurt
I have never enjoyed picking up a .60 sized (or even a tiny .40) plane with the engine screaming at full throttle and pointing it skyward. The prop always seems way too close to my pretty face (No comments Bob) since my stubby arms aren't much longer than the prop. I have yet to figure out a way to feel anything but awkward (i.e. unsafe) doing so.
Kurt
Run-Up tables can also be used in a similiar manner.
12-22-2011, 01:00 PM
#97
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RE: Fuel line pinch test
ORIGINAL: HighPlains
It's that pesky acceleration Kurt, it pushes the clunk back and stretches the clunk line. One must also allow that clunk fuel line seems to grow slightly when exposed to fuel for long periods. I actually encountered this phenomena a couple years ago in a beginners plane. So leaving a gap of 1/4'' from the clunk to the rear of the tank is a good idea. Some suggest even filing a notch in the clunk, but I think that is overkill.
It's that pesky acceleration Kurt, it pushes the clunk back and stretches the clunk line. One must also allow that clunk fuel line seems to grow slightly when exposed to fuel for long periods. I actually encountered this phenomena a couple years ago in a beginners plane. So leaving a gap of 1/4'' from the clunk to the rear of the tank is a good idea. Some suggest even filing a notch in the clunk, but I think that is overkill.
OK Bob. I just weighed an old clunk. It was 0.2 oz which is 0.0125 lbs. I then mounted a 5" length of fuel tubing on a hanging digital scale and found that I needed to pull approx. 1/2 of pound to get it to stretch 0.25 inches.
This means you would need to accelerate with 40g's on take-off to get the fuel tubing to stretch 1/4". I asked my wife to analyze the data and get back to be.
Kurt
12-22-2011, 01:01 PM
#98
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RE: Fuel line pinch test
ORIGINAL: opjose
I normally have novices place the fuse of the plane on a field table and hold it from the back so the prop is away from their face.
Run-Up tables can also be used in a similiar manner.
ORIGINAL: Bozarth
I have never enjoyed picking up a .60 sized (or even a tiny .40) plane with the engine screaming at full throttle and pointing it skyward. The prop always seems way too close to my pretty face (No comments Bob) since my stubby arms aren't much longer than the prop. I have yet to figure out a way to feel anything but awkward (i.e. unsafe) doing so.
Kurt
I have never enjoyed picking up a .60 sized (or even a tiny .40) plane with the engine screaming at full throttle and pointing it skyward. The prop always seems way too close to my pretty face (No comments Bob) since my stubby arms aren't much longer than the prop. I have yet to figure out a way to feel anything but awkward (i.e. unsafe) doing so.
Kurt
Run-Up tables can also be used in a similiar manner.
Kurt
12-22-2011, 01:25 PM
#99
RE: Fuel line pinch test
ORIGINAL: Bozarth
OK Bob. I just weighed an old clunk. It was 0.2 oz which is 0.0125 lbs. I then mounted a 5'' length of fuel tubing on a hanging digital scale and found that I needed to pull approx. 1/2 of pound to get it to stretch 0.25 inches.
This means you would need to accelerate with 40g's on take-off to get the fuel tubing to stretch 1/4''. I asked my wife to analyze the data and get back to be.
Kurt
ORIGINAL: HighPlains
It's that pesky acceleration Kurt, it pushes the clunk back and stretches the clunk line. One must also allow that clunk fuel line seems to grow slightly when exposed to fuel for long periods. I actually encountered this phenomena a couple years ago in a beginners plane. So leaving a gap of 1/4'' from the clunk to the rear of the tank is a good idea. Some suggest even filing a notch in the clunk, but I think that is overkill.
It's that pesky acceleration Kurt, it pushes the clunk back and stretches the clunk line. One must also allow that clunk fuel line seems to grow slightly when exposed to fuel for long periods. I actually encountered this phenomena a couple years ago in a beginners plane. So leaving a gap of 1/4'' from the clunk to the rear of the tank is a good idea. Some suggest even filing a notch in the clunk, but I think that is overkill.
OK Bob. I just weighed an old clunk. It was 0.2 oz which is 0.0125 lbs. I then mounted a 5'' length of fuel tubing on a hanging digital scale and found that I needed to pull approx. 1/2 of pound to get it to stretch 0.25 inches.
This means you would need to accelerate with 40g's on take-off to get the fuel tubing to stretch 1/4''. I asked my wife to analyze the data and get back to be.
Kurt
I've been bitten by this bug before, where the clunk seals itself off on the wall of the tank.
As far as pointing the nose of the plane up safely...that should be self explanatory for how to do it.
12-22-2011, 02:47 PM
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RE: Fuel line pinch test
Hi Guys, I read in a pattern site years ago how to build a tank,I took there advice and It worked great try to enter the tank with the engine line as close to the center of the tank.I usually use Sullivan tanks,and I solder a piece of 1/8" brass tubing to the clunk,make sure after you solder the clunk,clean it out with a drill bit. You only want 5/8" of flexibility, adding the additional weight of the tubing, the clunk will and must stay on the bottom of the tank when you rotate the tank 360 degrees. Make sure that the clunk is the most a 1/4" from the back of the tank,I usually use a piece of stripped telephone wire,to secure the fuel line to the clunk tubing,so it won't slide down in time.[:@]Now the clunk can't turn back, It's too long and the clunk is always in the fuel,no matter what position the plane is in.
I want to explain further,for a high speed needle valve setting,Pinch and HOLD the muffler line,sometimes for about 10 seconds,and listen,the rpms they should raise slightly about 300 rpms,if not you may be too lean,[&o]open it up a little,if it's too rich you will hear the rpms go higher. thanks Guys ED
try to enter the tank with the engine line as close to the center of the tank.I usually use Sullivan tanks,and I solder a piece of 1/8" brass tubing to the clunk,make sure after you solder the clunk,clean it out with a drill bit. You only want 5/8" of flexibility, adding the additional weight of the tubing, the clunk will and must stay on the bottom of the tank when you rotate the tank 360 degrees. Make sure that the clunk is the most a 1/4" from the back of the tank,I usually use a piece of stripped telephone wire,to secure the fuel line to the clunk tubing,so it won't slide down in time.[:@]Now the clunk can't turn back, It's too long and the clunk is always in the fuel,no matter what position the plane is in.I want to explain further,for a high speed needle valve setting,Pinch and HOLD the muffler line,sometimes for about 10 seconds,and listen,the rpms they should raise slightly about 300 rpms,if not you may be too lean,[&o]open it up a little,if it's too rich you will hear the rpms go higher.
thanks Guys ED