Today's Message Index:
----------------------
1. 08:51 AM - Re: [jabiruengines] EGTs and fuel quality (Lynn Matteson)
2. 10:00 AM - Re: Re: [jabiruengines] EGTs and fuel quality (Andy Silvester)
3. 11:40 AM - Re: Re: [jabiruengines] EGTs and fuel quality (Lynn Matteson)
4. 12:50 PM - Re: Re: [jabiruengines] EGTs and fuel quality (Lynn Matteson)
5. 01:26 PM - Re: Re: [jabiruengines] EGTs and fuel quality (Andy Silvester)
6. 01:56 PM - Re: Re: [jabiruengines] EGTs and fuel quality (Lynn Matteson)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: [jabiruengines] EGTs and fuel quality |
Andy-
Being another windy, gusty day, I decided to look into making the
ring and the guide vanes. (I have "before" temps that will suffice,
but really wanted to get current figures) Much to my surprise, when
I got the carb and rubber sleeve off, I saw that there was a ridge of
rubber between the carb side and the engine side. Maybe the rubber
sleeve manufacturer foresaw this gap as being a potential problem,
and decided to fill it. It is still not a perfect world, as the
rubber ridge is about .018" (about 1/2 mm) smaller in diameter than
the carb bore. That means it is about .009" lower all around than the
carb bore...no big deal, in my estimation. On the other side of the
ridge, though, the (I'll call it) adapter snout...the part that is
held onto the splitter housing/intake manifold with 4 bolts, is about
0.112" smaller than the ridge diameter, or 0.056" all around. This is
where I will concentrate my efforts. I'll chuck up this piece, bore
it to the carb diameter, and smooth and blend in this area. There is
plenty of meat in this piece and I don't feel I will get anywhere
near the groove in my efforts.
The other problem that I see is that the two components don't come
close enough together to touch the ridge on either side. The
impression of the two parts,the carb and adapter piece, in the rubber
look like they miss contacting the ridge by maybe 0.020"-0.030". So
there is that little area that could cause some turbulence, but not
as much as it would be if the ridge weren't there and a large gap
existed. I don't know if all the rubber sleeves are created equal, or
whether some were built without the ridge, or if I could find a
similar sleeve if/when I need one. I'll cross that bridge when I come
to it.
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/490+ hrs
On Apr 15, 2008, at 4:25 PM, Andy Silvester wrote:
> Lynn, Sounds like a good plan! I know others have tried without
> much success
> with guide vanes upstream of the carb, so don't be too disappointed
> if you
> can't get much from it. The theory is good, however! I don't know
> about the
> successes gained by the poster on the Sonextalk forum; I'm not a
> member and
> I didn't fancy joining just for one message. As you say, one thing
> at a time
> and measure as much as you can, analysing afterwards on the ground.
>
> Cheers, Andy
>
> From: jabiruengines@yahoogroups.com
> [mailto:jabiruengines@yahoogroups.com]
> On Behalf Of Lynn Matteson
> Sent: 15 April 2008 16:50
> To: jabiruengines@yahoogroups.com
> Subject: Re: [jabiruengines] EGTs and fuel quality
>
> Thanks, Andy. I was going to go up today and get some really good
> readings before I tore into the carb removal, ring building thing,
> but it was just too windy and gusty to get readings that would supply
> me with the "before" EGT's. Once I can get those, I'll go after the
> "gold ring." : ) I may even try some air-straightening vanes inside
> the tube just prior to the carb, but I want to do one thing at a time
> in order to know what did what.
>
> Lynn Matteson
> Grass Lake, Michigan
> Kitfox IV Speedster w/Jabiru 2200
> flying w/490+ hrs
>
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: [jabiruengines] EGTs and fuel quality |
Lynn,
OK, I'm a bit surprised by the existence of that 'ridge' as the ones I
inspected a while ago just had the two rounded ridges that locate in the
grooves in the carb body and the intake side adapter. In between there was a
gap, which I am suggesting filling. I guess the supplier changed the pattern
slightly. Also, it's really not the AIR we're interested in keeping out of
those spaces or grooves, it's FUEL. Remember, at around 12:1 - 14:1 air/fuel
ratio, it doesn't take much extra fuel to upset the ration big-time. As fuel
gets into that groove we think it swirls around due to air turbulence and
then exits back into the airstream in an uncontrolled way, meaning that
'splashes' of fuel are re-introduced downstream of the carb. These splashes
may-well form a liquid stream at some rpms and go down either the left or
right side of the splitter, causing the mixture imbalance. The idea of the
ring is to make as smooth a bore as possible right into the splitter from
the carburettor, so the mixture of fuel and air has a better chance of going
50/50 past the splitter. Any left/right EGT (mixture) differences would then
be due to turbulence or twisting of the air through the carb, and this could
be improved by the guide vanes. I recommend doing whatever's needed to
smooth-out the bore of the carb/coupler/adapter combination first, then
tackle any turbulence separately before the carb in the intake system. In
practice and if you have the right tool rake and cutting speed, you might
use a boring tool to remove the existing ridge inside the coupler, then you
have more space to fit a gap-ring. As always, more than one way to
accomplish the job but the result should be the same.
Hope this helps
Andy
-----Original Message-----
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of Lynn
Matteson
Sent: 16 April 2008 12:48
Subject: JabiruEngine-List: Re: [jabiruengines] EGTs and fuel quality
Andy-
Being another windy, gusty day, I decided to look into making the
ring and the guide vanes. (I have "before" temps that will suffice,
but really wanted to get current figures) Much to my surprise, when
I got the carb and rubber sleeve off, I saw that there was a ridge of
rubber between the carb side and the engine side. Maybe the rubber
sleeve manufacturer foresaw this gap as being a potential problem,
and decided to fill it. It is still not a perfect world, as the
rubber ridge is about .018" (about 1/2 mm) smaller in diameter than
the carb bore. That means it is about .009" lower all around than the
carb bore...no big deal, in my estimation. On the other side of the
ridge, though, the (I'll call it) adapter snout...the part that is
held onto the splitter housing/intake manifold with 4 bolts, is about
0.112" smaller than the ridge diameter, or 0.056" all around. This is
where I will concentrate my efforts. I'll chuck up this piece, bore
it to the carb diameter, and smooth and blend in this area. There is
plenty of meat in this piece and I don't feel I will get anywhere
near the groove in my efforts.
The other problem that I see is that the two components don't come
close enough together to touch the ridge on either side. The
impression of the two parts,the carb and adapter piece, in the rubber
look like they miss contacting the ridge by maybe 0.020"-0.030". So
there is that little area that could cause some turbulence, but not
as much as it would be if the ridge weren't there and a large gap
existed. I don't know if all the rubber sleeves are created equal, or
whether some were built without the ridge, or if I could find a
similar sleeve if/when I need one. I'll cross that bridge when I come
to it.
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/490+ hrs
On Apr 15, 2008, at 4:25 PM, Andy Silvester wrote:
> Lynn, Sounds like a good plan! I know others have tried without
> much success
> with guide vanes upstream of the carb, so don't be too disappointed
> if you
> can't get much from it. The theory is good, however! I don't know
> about the
> successes gained by the poster on the Sonextalk forum; I'm not a
> member and
> I didn't fancy joining just for one message. As you say, one thing
> at a time
> and measure as much as you can, analysing afterwards on the ground.
>
> Cheers, Andy
>
> From: jabiruengines@yahoogroups.com
> [mailto:jabiruengines@yahoogroups.com]
> On Behalf Of Lynn Matteson
> Sent: 15 April 2008 16:50
> To: jabiruengines@yahoogroups.com
> Subject: Re: [jabiruengines] EGTs and fuel quality
>
> Thanks, Andy. I was going to go up today and get some really good
> readings before I tore into the carb removal, ring building thing,
> but it was just too windy and gusty to get readings that would supply
> me with the "before" EGT's. Once I can get those, I'll go after the
> "gold ring." : ) I may even try some air-straightening vanes inside
> the tube just prior to the carb, but I want to do one thing at a time
> in order to know what did what.
>
> Lynn Matteson
> Grass Lake, Michigan
> Kitfox IV Speedster w/Jabiru 2200
> flying w/490+ hrs
>
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: [jabiruengines] EGTs and fuel quality |
I just got done boring out the adapter to the same diameter as the
ridge in the coupler....about 1.672"...and blended the various
machining operation marks out with a rubberized abrasive polishing
"stone." Now the carb, coupler and adapter are fairly smooth in
transition, all being about the same diameter, give or take a few
thousandths.
Next on the agenda is making the vanes. The pictures I've seen of the
vanes show them as being short, but I'd really like to make mine
follow the curve of the entire 6" long (measured right down the
middle), 90 fiberglas tube that I made. In order to do it right, I
might have to cut it in half...again...and insert the vanes, then
'glass it back together again.
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/490+ hrs
On Apr 16, 2008, at 12:55 PM, Andy Silvester wrote:
> <andy@suncoastjabiru.com>
>
> Lynn,
>
> OK, I'm a bit surprised by the existence of that 'ridge' as the ones I
> inspected a while ago just had the two rounded ridges that locate
> in the
> grooves in the carb body and the intake side adapter. In between
> there was a
> gap, which I am suggesting filling. I guess the supplier changed
> the pattern
> slightly. Also, it's really not the AIR we're interested in keeping
> out of
> those spaces or grooves, it's FUEL. Remember, at around 12:1 - 14:1
> air/fuel
> ratio, it doesn't take much extra fuel to upset the ration big-
> time. As fuel
> gets into that groove we think it swirls around due to air
> turbulence and
> then exits back into the airstream in an uncontrolled way, meaning
> that
> 'splashes' of fuel are re-introduced downstream of the carb. These
> splashes
> may-well form a liquid stream at some rpms and go down either the
> left or
> right side of the splitter, causing the mixture imbalance. The idea
> of the
> ring is to make as smooth a bore as possible right into the
> splitter from
> the carburettor, so the mixture of fuel and air has a better chance
> of going
> 50/50 past the splitter. Any left/right EGT (mixture) differences
> would then
> be due to turbulence or twisting of the air through the carb, and
> this could
> be improved by the guide vanes. I recommend doing whatever's needed to
> smooth-out the bore of the carb/coupler/adapter combination first,
> then
> tackle any turbulence separately before the carb in the intake
> system. In
> practice and if you have the right tool rake and cutting speed, you
> might
> use a boring tool to remove the existing ridge inside the coupler,
> then you
> have more space to fit a gap-ring. As always, more than one way to
> accomplish the job but the result should be the same.
>
> Hope this helps
>
> Andy
>
> -----Original Message-----
> From: owner-jabiruengine-list-server@matronics.com
> [mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of
> Lynn
> Matteson
> Sent: 16 April 2008 12:48
> To: jabiruengines@yahoogroups.com; jabiruengine-list@matronics.com
> Subject: JabiruEngine-List: Re: [jabiruengines] EGTs and fuel quality
>
> <lynnmatt@jps.net>
>
> Andy-
> Being another windy, gusty day, I decided to look into making the
> ring and the guide vanes. (I have "before" temps that will suffice,
> but really wanted to get current figures) Much to my surprise, when
> I got the carb and rubber sleeve off, I saw that there was a ridge of
> rubber between the carb side and the engine side. Maybe the rubber
> sleeve manufacturer foresaw this gap as being a potential problem,
> and decided to fill it. It is still not a perfect world, as the
> rubber ridge is about .018" (about 1/2 mm) smaller in diameter than
> the carb bore. That means it is about .009" lower all around than the
> carb bore...no big deal, in my estimation. On the other side of the
> ridge, though, the (I'll call it) adapter snout...the part that is
> held onto the splitter housing/intake manifold with 4 bolts, is about
> 0.112" smaller than the ridge diameter, or 0.056" all around. This is
> where I will concentrate my efforts. I'll chuck up this piece, bore
> it to the carb diameter, and smooth and blend in this area. There is
> plenty of meat in this piece and I don't feel I will get anywhere
> near the groove in my efforts.
>
> The other problem that I see is that the two components don't come
> close enough together to touch the ridge on either side. The
> impression of the two parts,the carb and adapter piece, in the rubber
> look like they miss contacting the ridge by maybe 0.020"-0.030". So
> there is that little area that could cause some turbulence, but not
> as much as it would be if the ridge weren't there and a large gap
> existed. I don't know if all the rubber sleeves are created equal, or
> whether some were built without the ridge, or if I could find a
> similar sleeve if/when I need one. I'll cross that bridge when I come
> to it.
>
>
> Lynn Matteson
> Grass Lake, Michigan
> Kitfox IV Speedster w/Jabiru 2200
> flying w/490+ hrs
>
>
> On Apr 15, 2008, at 4:25 PM, Andy Silvester wrote:
>
>> Lynn, Sounds like a good plan! I know others have tried without
>> much success
>> with guide vanes upstream of the carb, so don't be too disappointed
>> if you
>> can't get much from it. The theory is good, however! I don't know
>> about the
>> successes gained by the poster on the Sonextalk forum; I'm not a
>> member and
>> I didn't fancy joining just for one message. As you say, one thing
>> at a time
>> and measure as much as you can, analysing afterwards on the ground.
>>
>> Cheers, Andy
>>
>> From: jabiruengines@yahoogroups.com
>> [mailto:jabiruengines@yahoogroups.com]
>> On Behalf Of Lynn Matteson
>> Sent: 15 April 2008 16:50
>> To: jabiruengines@yahoogroups.com
>> Subject: Re: [jabiruengines] EGTs and fuel quality
>>
>> Thanks, Andy. I was going to go up today and get some really good
>> readings before I tore into the carb removal, ring building thing,
>> but it was just too windy and gusty to get readings that would supply
>> me with the "before" EGT's. Once I can get those, I'll go after the
>> "gold ring." : ) I may even try some air-straightening vanes inside
>> the tube just prior to the carb, but I want to do one thing at a time
>> in order to know what did what.
>>
>> Lynn Matteson
>> Grass Lake, Michigan
>> Kitfox IV Speedster w/Jabiru 2200
>> flying w/490+ hrs
>>
>
>
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: [jabiruengines] EGTs and fuel quality |
Here's a picture of my coupler, Andy and interested others, with the
parting line of the mold running right around the middle of the
ridge. You should be able to see the two "bumps", one on either side
that locate the adapter and the carb. As this is my used coupler, you
might also see a slight dimple between the ridge and the bump....this
is where the carb or the adapter didn't come all the way into contact
with the ridge, and it looks worse than it really is because of the
shiny highlight on it.
I'm awfully tempted to apply an RTV product right next to the ridge
before assembly, then assemble carb, coupler and adapter together.
Then reach inside and wipe off any squeezed-out RTV, before bolting
the whole assembly to the engine. how about it, Andy...think that'll
fill in the VERY little gap left between the carb and coupler, and
the adapter and coupler?
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/490+ hrs
On Apr 16, 2008, at 12:55 PM, Andy Silvester wrote:
> <andy@suncoastjabiru.com>
>
> Lynn,
>
> OK, I'm a bit surprised by the existence of that 'ridge' as the ones I
> inspected a while ago just had the two rounded ridges that locate
> in the
> grooves in the carb body and the intake side adapter. In between
> there was a
> gap, which I am suggesting filling. I guess the supplier changed
> the pattern
> slightly. Also, it's really not the AIR we're interested in keeping
> out of
> those spaces or grooves, it's FUEL. Remember, at around 12:1 - 14:1
> air/fuel
> ratio, it doesn't take much extra fuel to upset the ration big-
> time. As fuel
> gets into that groove we think it swirls around due to air
> turbulence and
> then exits back into the airstream in an uncontrolled way, meaning
> that
> 'splashes' of fuel are re-introduced downstream of the carb. These
> splashes
> may-well form a liquid stream at some rpms and go down either the
> left or
> right side of the splitter, causing the mixture imbalance. The idea
> of the
> ring is to make as smooth a bore as possible right into the
> splitter from
> the carburettor, so the mixture of fuel and air has a better chance
> of going
> 50/50 past the splitter. Any left/right EGT (mixture) differences
> would then
> be due to turbulence or twisting of the air through the carb, and
> this could
> be improved by the guide vanes. I recommend doing whatever's needed to
> smooth-out the bore of the carb/coupler/adapter combination first,
> then
> tackle any turbulence separately before the carb in the intake
> system. In
> practice and if you have the right tool rake and cutting speed, you
> might
> use a boring tool to remove the existing ridge inside the coupler,
> then you
> have more space to fit a gap-ring. As always, more than one way to
> accomplish the job but the result should be the same.
>
> Hope this helps
>
> Andy
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: [jabiruengines] EGTs and fuel quality |
Lynn,
A picture's worth a thousand words! That coupler is different to the older
ones. Imagine the central ridge not being there, and that was where I
proposed the additional ring should be. It's a little disappointing to see,
as I was hoping for a big improvement in mixture distribution from your
efforts. Nevertheless, I still think the joints between the 3 parts have a
bearing on the way the fuel / air mixture (or more probably liquid fuel and
air separately) flows down the pipe. I like the idea of RTV as a gap-seal,
as long as it stays-put. The worst case scenario is that a sliver of sealant
gets sucked into a cylinder - so what? I doubt very much it would block
anything in the induction path or burn to form a hard piece causing damage.
Others here might think of something I haven't but for now, it seems like a
simple, cheap and effective solution. Once this is done if it makes
negligible difference, then it HAS to be the air flowing thro' the carb in a
helix, which we pretty-much knew anyway.
Cheers, Andy
-----Original Message-----
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of Lynn
Matteson
Sent: 16 April 2008 16:45
Subject: Re: JabiruEngine-List: Re: [jabiruengines] EGTs and fuel quality
Here's a picture of my coupler, Andy and interested others, with the parting
line of the mold running right around the middle of the ridge. You should be
able to see the two "bumps", one on either side that locate the adapter and
the carb. As this is my used coupler, you might also see a slight dimple
between the ridge and the bump....this is where the carb or the adapter
didn't come all the way into contact with the ridge, and it looks worse than
it really is because of the shiny highlight on it.
I'm awfully tempted to apply an RTV product right next to the ridge before
assembly, then assemble carb, coupler and adapter together.
Then reach inside and wipe off any squeezed-out RTV, before bolting the
whole assembly to the engine. how about it, Andy...think that'll fill in the
VERY little gap left between the carb and coupler, and the adapter and
coupler?
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: [jabiruengines] EGTs and fuel quality |
Thanks, Andy....somebody at the coupling factory must have read your
mind, because they sure made that gap go away. And just as we were
going to get rich over building rings! : )
When I bored out the aluminum intake snout, that took an almost 1/16"
mis-match in diameters out of the way of the airflow, so maybe a
little was gained in looking into the gap situation, and perhaps not
all the couplings ARE made with the gap-filling ridge, so it behooves
owners to have a look and see.
I just slit my curved fiberglas tube down the middle, and will make
vanes to insert before I close it up again. I'll take pictures as I
go so if anybody wants to copy it...IF IT WORKS...they can. In the
meantime, let the winds blow and the rains come...I'm down for a day
or so. : )
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/490+ hrs
On Apr 16, 2008, at 4:23 PM, Andy Silvester wrote:
> <andy@suncoastjabiru.com>
>
> Lynn,
>
> A picture's worth a thousand words! That coupler is different to
> the older
> ones. Imagine the central ridge not being there, and that was where I
> proposed the additional ring should be. It's a little disappointing
> to see,
> as I was hoping for a big improvement in mixture distribution from
> your
> efforts. Nevertheless, I still think the joints between the 3 parts
> have a
> bearing on the way the fuel / air mixture (or more probably liquid
> fuel and
> air separately) flows down the pipe. I like the idea of RTV as a
> gap-seal,
> as long as it stays-put. The worst case scenario is that a sliver
> of sealant
> gets sucked into a cylinder - so what? I doubt very much it would
> block
> anything in the induction path or burn to form a hard piece causing
> damage.
> Others here might think of something I haven't but for now, it
> seems like a
> simple, cheap and effective solution. Once this is done if it makes
> negligible difference, then it HAS to be the air flowing thro' the
> carb in a
> helix, which we pretty-much knew anyway.
>
> Cheers, Andy
>
> -----Original Message-----
> From: owner-jabiruengine-list-server@matronics.com
> [mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of
> Lynn
> Matteson
> Sent: 16 April 2008 16:45
> To: jabiruengine-list@matronics.com
> Subject: Re: JabiruEngine-List: Re: [jabiruengines] EGTs and fuel
> quality
>
> Here's a picture of my coupler, Andy and interested others, with
> the parting
> line of the mold running right around the middle of the ridge. You
> should be
> able to see the two "bumps", one on either side that locate the
> adapter and
> the carb. As this is my used coupler, you might also see a slight
> dimple
> between the ridge and the bump....this is where the carb or the
> adapter
> didn't come all the way into contact with the ridge, and it looks
> worse than
> it really is because of the shiny highlight on it.
>
> I'm awfully tempted to apply an RTV product right next to the ridge
> before
> assembly, then assemble carb, coupler and adapter together.
> Then reach inside and wipe off any squeezed-out RTV, before bolting
> the
> whole assembly to the engine. how about it, Andy...think that'll
> fill in the
> VERY little gap left between the carb and coupler, and the adapter and
> coupler?
>
>
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|