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-   -   Gas tank - two line plumbing plan (http://www.rcuniverse.com/forum/gas-engines-142/11365590-gas-tank-two-line-plumbing-plan.html)

grosbeak 01-11-2013 07:37 AM

Gas tank - two line plumbing plan
 
Here's my plan for plumbing the DA-50 in my Sbach.

http://farm9.staticflickr.com/8497/8...0ea73c9b_z.jpg

I have heard conflicting reports about felt fibres from the clunk migrating through the supply line to the carb. I have also heard that dirt or debris around the fuel dot may make it into the system. The filter in the supply line on the carb side of the T fitting should take care of either issue.

rmh 01-11-2013 08:10 AM

RE: Gas tank - two line plumbing plan
 
FWIW = ditch BOTH filters
put one good filter on the outlet of the fuel can and one big filter in bottom of fuel can.
Fuel starvation on the engine is slow but certian problem using felt in tank filters and with some inline filters
If you do a good tank cleaning before running the engine and force fuel through a filter such as you show in your sketch- (not the tank filter, ditch that one ) you should be in good shape - then remove the filter in the fuel line. Simply filter all fuel going into the tank.

MTK 01-11-2013 08:13 AM

RE: Gas tank - two line plumbing plan
 

Quote:

ORIGINAL: grosbeak

Here's my plan for plumbing the DA-50 in my Sbach.

http://farm9.staticflickr.com/8497/8...0ea73c9b_z.jpg

I have heard conflicting reports about felt fibres from the clunk migrating through the supply line to the carb. I have also heard that dirt or debris around the fuel dot may make it into the system. The filter in the supply line on the carb side of the T fitting should take care of either issue.
That's the way I've done tanks for 25 years, glow and now gasoline. The felt klunk takes care of any bubbles the tank installation might cause...

If you need fittings, PM me or email me directly.Also sellone of the best gas lines available as well, inexpensive!

BarracudaHockey 01-11-2013 08:41 AM

RE: Gas tank - two line plumbing plan
 
+1 same way all my gassers are setup
Viton clunk line, walboro felt clunks, gemdot fuel dots

pe reivers 01-11-2013 10:00 AM

RE: Gas tank - two line plumbing plan
 
The t-line proved a source of problems. No more two-line system for me.
Three line with felt clunk pickup is the norm over here.

rmh 01-11-2013 10:47 AM

RE: Gas tank - two line plumbing plan
 
Whatever works for you - restrictions of any kind in the fuel pickup line are not desireable -in my book - I also have done this for a little while

pe reivers 01-11-2013 02:22 PM

RE: Gas tank - two line plumbing plan
 
I rather have a filter in the line than crap in the carb where it can really block fuel flow.

rmh 01-11-2013 02:34 PM

RE: Gas tank - two line plumbing plan
 

Quote:

ORIGINAL: pe reivers

I rather have a filter in the line than crap in the carb where it can really block fuel flow.

If there is no crap going into the tank - there is no crap going into the carb. That is my approach.
In line filters , especially he felt things, do plug up- and or restrict .
I do use a big felt filter in the fuel can and toss it if pumping slows.
If you have no problems with your setup - use it
I have no problems with mine either .
I know you have been at this for quite a while -
so have I .
There is more than one approach which works .

pe reivers 01-11-2013 02:56 PM

RE: Gas tank - two line plumbing plan
 
Fact is that I saw several problems using a two line system, and none with a three line system. If it works for you, fine.

captinjohn 01-11-2013 05:02 PM

RE: Gas tank - two line plumbing plan
 

Quote:

ORIGINAL: pe reivers

The t-line proved a source of problems. No more two-line system for me.
Three line with felt clunk pickup is the norm over here.

I now use 3 line and like it a lot. Also like rmh says....filter your fuelwith good filters. The best !!!!! Capt,nhttp://www.rcuniverse.com/forum/js/f.../thumbs_up.gif

rmh 01-11-2013 05:08 PM

RE: Gas tank - two line plumbing plan
 
Use what you like -
If you are into involved aerobatics - consider this :
the 3 line setups piddle fuel when the plane is held nose down.
Our setup for yeeeears was to do a clunk and a Tee in the line to the carb

The tank vent line (single) went from front top - out and around th e back of the tank to th e front and then down to bottom of the model facing into the airstream.
This prevents piddling when you pick up the plane
as for filters in the tank - No way Jose!
filter fuel going into the tank- and return fuel from model back into can-thru a sepearte line- this insures fuel flow thru the filler filter is outbound only -fully filtered.
also never use those filler valves which switch from fill to run- they leak air more often than not.
This simple system is easy to trouble shoot -
Weflew these setup in competition- and couldn't afford problems
When getting a quick start and reliable running counts The simple setup is always the best .
My opinion- do as you think best for you.

WindGap 01-11-2013 05:37 PM

RE: Gas tank - two line plumbing plan
 
I like your diagram. You spent good time on it. :) I have run into problems with this setup which I don't see with the three line setup. If you pump gas with some pressure, it can potentially overflow into the carb and flood it. This was the case for my gas saito. Once flooded, it wouldn't start till cleared up. YMMV

MTK 01-11-2013 06:38 PM

RE: Gas tank - two line plumbing plan
 


The felt filter in the tank helps eliminate bubbles. I had one tank installation that no matter what I did, it would generate bubbles and these found their way to the carb. It is a gas application and although the engine didn't quit, it would try. Very annoying. The felt filter has helped and I fill the tank through it to boot.

But I also tripple filter the supply....We can't afford hic-ups in neither comps nor practice</p>

dadragon 01-11-2013 07:15 PM

RE: Gas tank - two line plumbing plan
 
I have always used a 3 line system, RMH +1,

drac1 01-12-2013 03:52 AM

RE: Gas tank - two line plumbing plan
 
I use two line systems in my gas planes. No felt clunk just a brass clunk in the tank, a tee with fuel dot and an inline filter before the carb. Naturally the fuel is filtered before it goes into the model.
I have never had a fuel system problem, fuel starvation problem or engine stoppages with this set up.
What ever set up you use, be meticulous with the plumbing and things should be OK.

BarracudaHockey 01-12-2013 05:16 AM

RE: Gas tank - two line plumbing plan
 
If the felt makes you nervous get the ceramic pickup

As for downlines, I dont think you could fly one long enough to fuel starve an engine

av8tor1977 01-12-2013 06:57 AM

RE: Gas tank - two line plumbing plan
 
I've switched to the three line system myself and like it. I also agree about using a felt clunk, and NEVER using a fill valve of any sort.

AV8TOR

BobH 01-12-2013 07:15 AM

RE: Gas tank - two line plumbing plan
 
Many years ago when I worked in the chain saw industry felt filtlers were the standard. The only issue with them is that after a while they tend to harden and restrict fuel. If you are aware of that and change them befor that happens you are fine. No fibers get in the carb etc. These filters are made specifically for their intended purpose.
Walboro carbs take about 10psi or more to over come the inlet needle valve. So fueling on the two line system would only be an issue if you have a lot of fuel pressure in that line. FYI I've always used a 3 line system but I don't see big problems with either situation provided you do the right things in the first place.

Lnewqban 01-12-2013 07:54 AM

RE: Gas tank - two line plumbing plan
 
grosbeak,

I did rate your schematic (5 stars); it is great.

Your carburetor has a pump that will overcome the increasing restriction of both filters up to certain point.

Your engine will tell you when they have become clogged, via the symptoms of lean mix.

If the tank filter gets clogged first, the vacuum action of the pump may make the fill up port fail and introduce some air into the carb.

av8tor1977 01-12-2013 10:35 AM

RE: Gas tank - two line plumbing plan
 

Quote:

ORIGINAL: BobH

Many years ago when I worked in the chain saw industry felt filtlers were the standard. The only issue with them is that after a while they tend to harden and restrict fuel. If you are aware of that and change them befor that happens you are fine. No fibers get in the carb etc. These filters are made specifically for their intended purpose.
Walboro carbs take about 10psi or more to over come the inlet needle valve. So fueling on the two line system would only be an issue if you have a lot of fuel pressure in that line. FYI I've always used a 3 line system but I don't see big problems with either situation provided you do the right things in the first place.
I am quite careful about my plumbing; always using wire to wrap each connection, etc., so I never had a problem with the two line with a "T" system. But what I didn't like was each time you fuel the plane, you are filling it through the wrong side of the fiilter clunk and it is possible to introduce crap straight into the line the goes to the carb. You also introduce air into the inlet fuel line. For me that sometimes that would cause a delay in the re-start until the line got filled back up. Not always, but I have had it occur.

AV8TOR

rmh 01-12-2013 11:28 AM

RE: Gas tank - two line plumbing plan
 
If your engine (the carb) is correct- there is no problem-
you can NOT force fuel into the carb and with no filter in the clunk and the ONLY filters in the fuel can - -you simply fill the tank.
again if the carb is correct -
a full choke will pull fuel quickly thru the clunk line and this fuel will NOT flow back into the tank.
Having spent a few years testing all the new engine designs from an importer as well as doing write ups on various or brand gassers for magazines -I saw no exceptions to this - If you know of any - please let me know.

OldScaleGuy 01-12-2013 01:05 PM

RE: Gas tank - two line plumbing plan
 
1 Attachment(s)

Quote:

ORIGINAL: rmh

If your engine (the carb) is correct- there is no problem-
you can NOT force fuel into the carb and with no filter in the clunk and the ONLY filters in the fuel can - -you simply fill the tank.
again if the carb is correct -
a full choke will pull fuel quickly thru the clunk line and this fuel will NOT flow back into the tank.
Having spent a few years testing all the new engine designs from an importer as well as doing write ups on various or brand gassers for magazines -I saw no exceptions to this - If you know of any - please let me know.
Not to get to far off subject but with your experience i would like to hear which engines you think are #1, #2, #3, etc. as far as quality and reliability.
(Sara is watching).....:)

Granpooba 01-12-2013 03:27 PM

RE: Gas tank - two line plumbing plan
 
Looks like the fuel system on Boeings new Dreamliner. And that ones leaking. :)

Ernie Misner 01-12-2013 04:13 PM

RE: Gas tank - two line plumbing plan
 
All the guys who are running a 3 line setup..... are you talking 2 clunks + 1 vent line?

Lightspeed1551 01-12-2013 05:04 PM

RE: Gas tank - two line plumbing plan
 
I'm running 3. A clunked fill/drain line that is caped during flight, a clunked engine pick up, and a vent with the brass tube bent up. Also I only have filters on my gas can too.

I love this filler and cap assembly . http://www.bennettbuilt.com/shop/Tan..._Fittings.html


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