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don.honabach(at)pcperfect
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 Posted: Mon Jan 12, 2009 10:05 pm Post subject: 3300A - Full Throttle Roughness |
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I'm having an issue where during cruise flight if I go full throttle either in straight and level or climb, the engine gets rough enough that it feels like it will quit. At this point, I obviously don't want to push the issue so I pull back on the throttle until the roughness goes away.
Interestingly, I have no problem with full throttle roughness on take-off/climb-out.
I also did some additional testing today and found that if I ease real slow into full throttle from cruise that I still get the roughness but not as bad and that the RPM will increase up to ~2,9xx and then start to degrade as I continue to add power along with additional roughness.
Background info:
Full Throttle Static RPM/Ground Run Up is ~2,800RPM. No issues with roughness.
On my 601HDS, I have a 3300A with the Sensenich Carbon Prop (64"? 2A0J5R64Z-N) that was purchased from Jabiru USA/Pete K. back in 2006.
Any help greatly appreciated. I've sent this same question to Jabiru USA and haven't gotten a response yet (sent last Thursday and sent another today asking for status).
Initially thought it was the SCAT intake hose which I replaced with the rubber 90 degree elbow. Same issue with either intake method.
Thanks!
Don Honabach
Tempe, AZ
[quote][b]
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Peter H
Joined: 20 Mar 2007
Posts: 197
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| Posted: Mon Jan 12, 2009 10:23 pm Post subject: 3300A - Full Throttle Roughness |
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It sounds like it may be too rich under the load conditions at WOT cruise.
The fuel bowl is fitted with 2.25mm needle valve seat which is meant for gravity feed, but they have selected the power needle as a compromise. If you are using a fuel pump it may cause the needle valve seat to leak and overfill the fuel bowl causing excessive rich mixture near max rpm.
Another cause of over rich mixture is due to the starting choke not fully closing due to friction in the cable.
Peter
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Don Honabach
Sent: Tuesday, 13 January 2009 4:03 PM
To: jabiruengine-list(at)matronics.com
Subject: 3300A - Full Throttle Roughness
I'm having an issue where during cruise flight if I go full throttle either in straight and level or climb, the engine gets rough enough that it feels like it will quit. At this point, I obviously don't want to push the issue so I pull back on the throttle until the roughness goes away.
Interestingly, I have no problem with full throttle roughness on take-off/climb-out.
I also did some additional testing today and found that if I ease real slow into full throttle from cruise that I still get the roughness but not as bad and that the RPM will increase up to ~2,9xx and then start to degrade as I continue to add power along with additional roughness.
Background info:
Full Throttle Static RPM/Ground Run Up is ~2,800RPM. No issues with roughness.
On my 601HDS, I have a 3300A with the Sensenich Carbon Prop (64"? 2A0J5R64Z-N) that was purchased from Jabiru USA/Pete K. back in 2006.
Any help greatly appreciated. I've sent this same question to Jabiru USA and haven't gotten a response yet (sent last Thursday and sent another today asking for status).
Initially thought it was the SCAT intake hose which I replaced with the rubber 90 degree elbow. Same issue with either intake method.
Thanks!
Don Honabach
Tempe, AZ
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don(at)pcperfect.com
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| Posted: Mon Jan 12, 2009 10:35 pm Post subject: 3300A - Full Throttle Roughness |
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I'm having an issue where during cruise flight if I go full throttle either in straight and level or climb, the engine gets rough enough that it feels like it will quit. At this point, I obviously don't want to push the issue so I pull back on the throttle until the roughness goes away.
Interestingly, I have no problem with full throttle roughness on take-off/climb-out.
I also did some additional testing today and found that if I ease real slow into full throttle from cruise that I still get the roughness but not as bad and that the RPM will increase up to ~2,9xx and then start to degrade as I continue to add power along with additional roughness.
Background info:
Full Throttle Static RPM/Ground Run Up is ~2,800RPM. No issues with roughness.
On my 601HDS, I have a 3300A with the Sensenich Carbon Prop (64"? 2A0J5R64Z-N) that was purchased from Jabiru USA/Pete K. back in 2006.
Any help greatly appreciated. I've sent this same question to Jabiru USA and haven't gotten a response yet (sent last Thursday and sent another today asking for status).
Initially thought it was the SCAT intake hose which I replaced with the rubber 90 degree elbow. Same issue with either intake method.
Thanks!
Don Honabach
Tempe, AZ
[quote][b]
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don(at)pcperfect.com
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| Posted: Mon Jan 12, 2009 10:58 pm Post subject: 3300A - Full Throttle Roughness |
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Peter,
Thanks for the quick reply.
FYI, I have a low-wing design and during take-off I use an electric boost pump but during transition to cruise I turn it off and just use the engine driven mechanical fuel pump on the 3300A. Even with the boost pump, I don't exceed 3PSI (at least as much as I can trust the accuracy of the gauge at such low values and a narrow range).
Assuming the needle leaking is the issue, is there a fix for non-gravity feed setups?
As a side question, do those with gravity setups remove the engine driven pump?
I'm assuming that if I turn on the boost pump during cruise and if I have a needle leak issue that the problem should be noticeable sooner or should be worse as the increased pressure will cause more leakage?
I'll check the choke cable as well to make sure it is fully closing.
Thanks!
Don
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Peter Harris
Sent: Monday, January 12, 2009 23:21
To: jabiruengine-list(at)matronics.com
Subject: RE: 3300A - Full Throttle Roughness
It sounds like it may be too rich under the load conditions at WOT cruise.
The fuel bowl is fitted with 2.25mm needle valve seat which is meant for gravity feed, but they have selected the power needle as a compromise. If you are using a fuel pump it may cause the needle valve seat to leak and overfill the fuel bowl causing excessive rich mixture near max rpm.
Another cause of over rich mixture is due to the starting choke not fully closing due to friction in the cable.
Peter
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Don Honabach
Sent: Tuesday, 13 January 2009 4:03 PM
To: jabiruengine-list(at)matronics.com
Subject: 3300A - Full Throttle Roughness
I'm having an issue where during cruise flight if I go full throttle either in straight and level or climb, the engine gets rough enough that it feels like it will quit. At this point, I obviously don't want to push the issue so I pull back on the throttle until the roughness goes away.
Interestingly, I have no problem with full throttle roughness on take-off/climb-out.
I also did some additional testing today and found that if I ease real slow into full throttle from cruise that I still get the roughness but not as bad and that the RPM will increase up to ~2,9xx and then start to degrade as I continue to add power along with additional roughness.
Background info:
Full Throttle Static RPM/Ground Run Up is ~2,800RPM. No issues with roughness.
On my 601HDS, I have a 3300A with the Sensenich Carbon Prop (64"? 2A0J5R64Z-N) that was purchased from Jabiru USA/Pete K. back in 2006.
Any help greatly appreciated. I've sent this same question to Jabiru USA and haven't gotten a response yet (sent last Thursday and sent another today asking for status).
Initially thought it was the SCAT intake hose which I replaced with the rubber 90 degree elbow. Same issue with either intake method.
Thanks!
Don Honabach
Tempe, AZ
0
No virus found in this incoming message.
Checked by AVG - http://www.avg.com
1/12/2009 07:04
[quote][b]
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Peter H
Joined: 20 Mar 2007
Posts: 197
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| Posted: Mon Jan 12, 2009 11:12 pm Post subject: 3300A - Full Throttle Roughness |
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Don
I have the J3300 in a Quickie Q-200 and getting 170KTS at 3000 ft CAS but still not happy with the higher power settings and feel it has more potential.
Yes you could try the boost pump and that would indicate if there is a problem with the needle valve seat. It is possible to almost stop the engine if it gets too rich even at WOT.
The setup is supposed to be OK at 3PSI.
Some have fitted a fuel pressure regulator but if you are sure you have 3PSI up to WOT I don’t see any value in adding another fail point.
Maybe it is the choke. The return spring is not very strong.
Peter
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Don Honabach
Sent: Tuesday, 13 January 2009 4:55 PM
To: jabiruengine-list(at)matronics.com
Subject: RE: JabiruEngine-List: 3300A - Full Throttle Roughness
Peter,
Thanks for the quick reply.
FYI, I have a low-wing design and during take-off I use an electric boost pump but during transition to cruise I turn it off and just use the engine driven mechanical fuel pump on the 3300A. Even with the boost pump, I don't exceed 3PSI (at least as much as I can trust the accuracy of the gauge at such low values and a narrow range).
Assuming the needle leaking is the issue, is there a fix for non-gravity feed setups?
As a side question, do those with gravity setups remove the engine driven pump?
I'm assuming that if I turn on the boost pump during cruise and if I have a needle leak issue that the problem should be noticeable sooner or should be worse as the increased pressure will cause more leakage?
I'll check the choke cable as well to make sure it is fully closing.
Thanks!
Don
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Peter Harris
Sent: Monday, January 12, 2009 23:21
To: jabiruengine-list(at)matronics.com
Subject: RE: JabiruEngine-List: 3300A - Full Throttle Roughness
It sounds like it may be too rich under the load conditions at WOT cruise.
The fuel bowl is fitted with 2.25mm needle valve seat which is meant for gravity feed, but they have selected the power needle as a compromise. If you are using a fuel pump it may cause the needle valve seat to leak and overfill the fuel bowl causing excessive rich mixture near max rpm.
Another cause of over rich mixture is due to the starting choke not fully closing due to friction in the cable.
Peter
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Don Honabach
Sent: Tuesday, 13 January 2009 4:03 PM
To: jabiruengine-list(at)matronics.com
Subject: 3300A - Full Throttle Roughness
I'm having an issue where during cruise flight if I go full throttle either in straight and level or climb, the engine gets rough enough that it feels like it will quit. At this point, I obviously don't want to push the issue so I pull back on the throttle until the roughness goes away.
Interestingly, I have no problem with full throttle roughness on take-off/climb-out.
I also did some additional testing today and found that if I ease real slow into full throttle from cruise that I still get the roughness but not as bad and that the RPM will increase up to ~2,9xx and then start to degrade as I continue to add power along with additional roughness.
Background info:
Full Throttle Static RPM/Ground Run Up is ~2,800RPM. No issues with roughness.
On my 601HDS, I have a 3300A with the Sensenich Carbon Prop (64"? 2A0J5R64Z-N) that was purchased from Jabiru USA/Pete K. back in 2006.
Any help greatly appreciated. I've sent this same question to Jabiru USA and haven't gotten a response yet (sent last Thursday and sent another today asking for status).
Initially thought it was the SCAT intake hose which I replaced with the rubber 90 degree elbow. Same issue with either intake method.
Thanks!
Don Honabach
Tempe, AZ
0
No virus found in this incoming message.
Checked by AVG - http://www.avg.com
1/12/2009 07:04 123456789 | Quote: | | http://www.matronics.com/Navigator?JabiruEngine-List |
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lgingell
Joined: 10 Jan 2006
Posts: 50
Location: Lake California Airpark 68CA
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| Posted: Tue Jan 13, 2009 12:50 am Post subject: Re: 3300A - Full Throttle Roughness |
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Don,
Check you EGT span. I had to modify my induction with a cheap rubber hose instead of SCAT tube, since I was running rought at WOT over 8000ft:
http://www.lancegingell.com/lance/Tuning_the_Zodiac.html
..lance
ZodiacXL/Jab3300 ~300hrs
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Zodiac XL/Jab 3300
http://lancegingell.com |
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Lynn Matteson
Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan
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| Posted: Tue Jan 13, 2009 1:33 am Post subject: 3300A - Full Throttle Roughness |
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I've gone to gravity only in my 2200 high-wing Kitfox, removing the
mechanical AND the electric pump (that I rarely used before), and
installed the 3.7 mm float needle seat that Bing recommended. No
fuel issues any more for me.
I would think that if you DID have a pressure-related problem with
the float needle/seat combo, that your suggestion of turning on the
boost pump ...at altitude....would reveal it. It did for me, when I
still had my electric pump. It was just too much pressure, so I
removed it, went with the gravity-only, and the 3.7 mm seat.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062, 600.2 hrs
Sensenich 62x46
flying again after engine rebuild, and new Electroair direct-fire
ignition system;
also building a new pair of snow skis
do not archive
On Jan 13, 2009, at 1:55 AM, Don Honabach wrote:
| Quote: | Peter,
Thanks for the quick reply.
FYI, I have a low-wing design and during take-off I use an electric
boost pump but during transition to cruise I turn it off and just
use the engine driven mechanical fuel pump on the 3300A. Even with
the boost pump, I don't exceed 3PSI (at least as much as I can
trust the accuracy of the gauge at such low values and a narrow
range).
Assuming the needle leaking is the issue, is there a fix for non-
gravity feed setups?
As a side question, do those with gravity setups remove the engine
driven pump?
I'm assuming that if I turn on the boost pump during cruise and if
I have a needle leak issue that the problem should be noticeable
sooner or should be worse as the increased pressure will cause more
leakage?
I'll check the choke cable as well to make sure it is fully closing.
Thanks!
Don
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-
jabiruengine-list-server(at)matronics.com] On Behalf Of Peter Harris
Sent: Monday, January 12, 2009 23:21
To: jabiruengine-list(at)matronics.com
Subject: RE: 3300A - Full Throttle Roughness
It sounds like it may be too rich under the load conditions at WOT
cruise.
The fuel bowl is fitted with 2.25mm needle valve seat which is
meant for gravity feed, but they have selected the power needle as
a compromise. If you are using a fuel pump it may cause the needle
valve seat to leak and overfill the fuel bowl causing excessive
rich mixture near max rpm.
Another cause of over rich mixture is due to the starting choke not
fully closing due to friction in the cable.
Peter
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-
jabiruengine-list-server(at)matronics.com] On Behalf Of Don Honabach
Sent: Tuesday, 13 January 2009 4:03 PM
To: jabiruengine-list(at)matronics.com
Subject: 3300A - Full Throttle Roughness
I'm having an issue where during cruise flight if I go full
throttle either in straight and level or climb, the engine gets
rough enough that it feels like it will quit. At this point, I
obviously don't want to push the issue so I pull back on the
throttle until the roughness goes away.
Interestingly, I have no problem with full throttle roughness on
take-off/climb-out.
I also did some additional testing today and found that if I ease
real slow into full throttle from cruise that I still get the
roughness but not as bad and that the RPM will increase up to
~2,9xx and then start to degrade as I continue to add power along
with additional roughness.
Background info:
Full Throttle Static RPM/Ground Run Up is ~2,800RPM. No issues with
roughness.
On my 601HDS, I have a 3300A with the Sensenich Carbon Prop (64"?
2A0J5R64Z-N) that was purchased from Jabiru USA/Pete K. back in 2006.
Any help greatly appreciated. I've sent this same question to
Jabiru USA and haven't gotten a response yet (sent last Thursday
and sent another today asking for status).
Initially thought it was the SCAT intake hose which I replaced with
the rubber 90 degree elbow. Same issue with either intake method.
Thanks!
Don Honabach
Tempe, AZ
http://www.matronics.com/Navigator?JabiruEngine-List http://
forums.matronics.com http://www.matronics.com/contribution
&nbssp; - The JabiruEngine-List Email Forum utilities such as
List Photoshare, and much much --> http://www.matronics.com/
Navigator?JabiruEngine-Listhttp://forums.matronics.com -
List Contribution Web generous nbsp; -->
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Checked by AVG - http://www.avg.com
1/12/2009 07:04
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Lynn
Kitfox IV-Jabiru 2200
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DaveG601XL
Joined: 27 Oct 2006
Posts: 351
Location: Cincinnati, Oh
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| Posted: Tue Jan 13, 2009 4:22 am Post subject: Re: 3300A - Full Throttle Roughness |
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Don,
Have you played with your jet sizes at all? I had a similar issue with being just a little rich at takeoff, but way too rich at WOT in straight and level flight. I had one speed run in which I had two cylinders actually go so cold in EGT that they shut down on me. That is the benefit of having instrumentation on all cylinders.
I went from the stock 255 main jet to a smaller 250. This helped out a lot. Interestingly enough, there is an interaction between the main and needle jets, even at WOT, when the main jet is supposed to be in control. I found this out when I started to tune in my cruise EGT and went from a stock 285 needle jet to a smaller 280. Going to the smaller needle jet made my WOT a little too lean now. I went back to the larger 255 main jet and I am pretty happy with it now.
Throw into the mix that I also went to a rubber intake hose with a flow divider to even the EGT spreads across the cylinders.
Your results will certainly vary, but that is why they call this experimental, right?
Good luck,
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David Gallagher
Cincinnati, OH area |
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icubob(at)newnorth.net
Guest
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| Posted: Tue Jan 13, 2009 4:42 am Post subject: 3300A - Full Throttle Roughness |
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don,
i have read some builders have removed the mech. pump with a gravity set up. very easy to make a cover plate where the mech. pump attaches.
a leaky needle valve can be a bad seat or needle, or your system is overpowering the float. bing can supply a new seat or needle. a pressure gauge that covers a very narrow pressure range can be had for less than $20. if you are overpressuring the carb it will leak. i think first i would want to know the fuel pressure, then decide the fix.
i have also seen my carb leak and run smooth on the ground.
bob noffs
---
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Float Flyr
Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland
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| Posted: Tue Jan 13, 2009 6:08 am Post subject: 3300A - Full Throttle Roughness |
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That sounds like a fuel delivery problem to me. Possibly a fuel pump not working properly when hot. If you have a fuel flow meter check your fuel flow as you approach full throttle. If yu have a fuel pressure gauge check that there is no drop in fuel pressure as the engine warms up .
Noel
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Don Honabach
Sent: Tuesday, January 13, 2009 2:33 AM
To: jabiruengine-list(at)matronics.com
Subject: 3300A - Full Throttle Roughness
I'm having an issue where during cruise flight if I go full throttle either in straight and level or climb, the engine gets rough enough that it feels like it will quit. At this point, I obviously don't want to push the issue so I pull back on the throttle until the roughness goes away.
Interestingly, I have no problem with full throttle roughness on take-off/climb-out.
I also did some additional testing today and found that if I ease real slow into full throttle from cruise that I still get the roughness but not as bad and that the RPM will increase up to ~2,9xx and then start to degrade as I continue to add power along with additional roughness.
Background info:
Full Throttle Static RPM/Ground Run Up is ~2,800RPM. No issues with roughness.
On my 601HDS, I have a 3300A with the Sensenich Carbon Prop (64"? 2A0J5R64Z-N) that was purchased from Jabiru USA/Pete K. back in 2006.
Any help greatly appreciated. I've sent this same question to Jabiru USA and haven't gotten a response yet (sent last Thursday and sent another today asking for status).
Initially thought it was the SCAT intake hose which I replaced with the rubber 90 degree elbow. Same issue with either intake method.
Thanks!
Don Honabach
Tempe, AZ
| Quote: | | http://www.matronics.com/Navigator?JabiruEngine-List |
0123456789
[quote][b]
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Noel Loveys
Kitfox III-A
Aerocet 1100 Floats |
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zeprep251(at)aol.com
Guest
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| Posted: Tue Jan 13, 2009 6:14 am Post subject: 3300A - Full Throttle Roughness |
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Don,
What happens to the exhaust gas temps when you get the roughness?
--
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Float Flyr
Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland
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| Posted: Tue Jan 13, 2009 6:21 am Post subject: 3300A - Full Throttle Roughness |
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The way to tell an over rich condition is to check the plugs. There will always be a good dose of soot on them if you land immediately. The fuel flow and pressure tests will show a rich condition too. Generally an over rich condition makes the engine sluggish and you start to have problems as you pull the throttle back as the plugs have to clear themselves enough to keep the engine running.
One other problem you may have is low octane rating on the fuel. That could sure cause your engine to get rough at top end rpm.
Noel
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Peter Harris
Sent: Tuesday, January 13, 2009 2:51 AM
To: jabiruengine-list(at)matronics.com
Subject: RE: 3300A - Full Throttle Roughness
It sounds like it may be too rich under the load conditions at WOT cruise.
The fuel bowl is fitted with 2.25mm needle valve seat which is meant for gravity feed, but they have selected the power needle as a compromise. If you are using a fuel pump it may cause the needle valve seat to leak and overfill the fuel bowl causing excessive rich mixture near max rpm.
Another cause of over rich mixture is due to the starting choke not fully closing due to friction in the cable.
Peter
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Don Honabach
Sent: Tuesday, 13 January 2009 4:03 PM
To: jabiruengine-list(at)matronics.com
Subject: 3300A - Full Throttle Roughness
I'm having an issue where during cruise flight if I go full throttle either in straight and level or climb, the engine gets rough enough that it feels like it will quit. At this point, I obviously don't want to push the issue so I pull back on the throttle until the roughness goes away.
Interestingly, I have no problem with full throttle roughness on take-off/climb-out.
I also did some additional testing today and found that if I ease real slow into full throttle from cruise that I still get the roughness but not as bad and that the RPM will increase up to ~2,9xx and then start to degrade as I continue to add power along with additional roughness.
Background info:
Full Throttle Static RPM/Ground Run Up is ~2,800RPM. No issues with roughness.
On my 601HDS, I have a 3300A with the Sensenich Carbon Prop (64"? 2A0J5R64Z-N) that was purchased from Jabiru USA/Pete K. back in 2006.
Any help greatly appreciated. I've sent this same question to Jabiru USA and haven't gotten a response yet (sent last Thursday and sent another today asking for status).
Initially thought it was the SCAT intake hose which I replaced with the rubber 90 degree elbow. Same issue with either intake method.
Thanks!
Don Honabach
Tempe, AZ
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Noel Loveys
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japhillipsga(at)aol.com
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| Posted: Tue Jan 13, 2009 7:56 am Post subject: 3300A - Full Throttle Roughness |
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Don, I had a similar problem even with the rubber hose. Seems the carb reacts to the varing speed of the air coming into it after the 90 degree turn. The fix was making a divider vane of .20 aluminum sized to slip snug inside the rubber tube at the bend that divides and channels the air just before it enters the Bing. Worked for me. Best of luck, Bill of Georgia
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aslsa.rng(at)gmail.com
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| Posted: Tue Jan 13, 2009 9:27 am Post subject: 3300A - Full Throttle Roughness |
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As a firm believer in doing the easiest, cheapest thing first, check your tank venting. Next, do a plug check. Let the engine enter its rough running, shut the engine off and glide in. Plug color is an inexact method, per the Bing manual, but if your engine is running so rich as to run rough you should see the fuel contamination on the insulator. Worth what you paid for it.
Rick
On Tue, Jan 13, 2009 at 9:53 AM, <japhillipsga(at)aol.com (japhillipsga(at)aol.com)> wrote:
[quote] Don, I had a similar problem even with the rubber hose. Seems the carb reacts to the varing speed of the air coming into it after the 90 degree turn. The fix was making a divider vane of .20 aluminum sized to slip snug inside the rubber tube at the bend that divides and channels the air just before it enters the Bing. Worked for me. Best of luck, Bill of Georgia
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Float Flyr
Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland
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| Posted: Tue Jan 13, 2009 10:19 am Post subject: 3300A - Full Throttle Roughness |
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Any engine running that rich, long enough, will leave lots of soot on the bottom of the plane and it will be caked up well in the exhaust too. Have a look. Little or no soot and the problem is not too rich.
Noel
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Richard Girard
Sent: Tuesday, January 13, 2009 1:54 PM
To: jabiruengine-list(at)matronics.com
Subject: Re: 3300A - Full Throttle Roughness
As a firm believer in doing the easiest, cheapest thing first, check your tank venting. Next, do a plug check. Let the engine enter its rough running, shut the engine off and glide in. Plug color is an inexact method, per the Bing manual, but if your engine is running so rich as to run rough you should see the fuel contamination on the insulator. Worth what you paid for it.
Rick
On Tue, Jan 13, 2009 at 9:53 AM, <japhillipsga(at)aol.com (japhillipsga(at)aol.com)> wrote:
Don, I had a similar problem even with the rubber hose. Seems the carb reacts to the varing speed of the air coming into it after the 90 degree turn. The fix was making a divider vane of .20 aluminum sized to slip snug inside the rubber tube at the bend that divides and channels the air just before it enters the Bing. Worked for me. Best of luck, Bill of Georgia
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Noel Loveys
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Peter H
Joined: 20 Mar 2007
Posts: 197
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| Posted: Tue Jan 13, 2009 1:06 pm Post subject: 3300A - Full Throttle Roughness |
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Lynn
According to the advice I got from the German Bing website engineer
The float valve needle seat for gravity feed is 2.25 and for pump feed is
1.5mm. I tried the 1,5mm seat and found it very I would say too lean at
cruise because Jab has selected the power needle using the 2.25 seat/pump
combination tuned for economy cruise.
I conducted bench tests of the induction collector using a pressure spray
gun and found that the alignment of the intake is absolutely critical due to
the fact that inside the collector is a central vane. Any misalignment of
the carb butterfly or of the carb on the hose attachment will cause the
charge to favour one side or the other. If the distribution of the charge is
bad the engine begins to "box" with uneven power strokes causing vibration
(which I think may contribute to the flywheel bolts breakage). In an extreme
case the engine may run bad rough.
Likewise poor scat hose configuration could contribute to the issue and the
effect is suddenly greatest at or near WOT.
Peter
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Peter H
Joined: 20 Mar 2007
Posts: 197
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| Posted: Tue Jan 13, 2009 1:23 pm Post subject: 3300A - Full Throttle Roughness |
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Even assuming the incoming charge is aligned properly, near WOT there is a large increase in fuel dumped at the end of the collector feeding #1 and #2 and this will show up on the plugs as suggested by Noel. I have been experimenting with a 1.5L tapered plenum in place of the Jab collector and the effect near WOT is dramatic causing breakdown and black smoke. Because of internal losses the Jab collector does not normally breakdown , but will usually run rich on #1 and #2 when the butterfly is near fully opened.
At smaller throttle settings the butterfly turbulence probably contributes to even distribution of the charge.
I discovered that it is not easy to design an intake to be fed from the end, it should be fed from the bottom but I have no space.
Peter
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Noel Loveys
Sent: Wednesday, 14 January 2009 12:19 AM
To: jabiruengine-list(at)matronics.com
Subject: RE: 3300A - Full Throttle Roughness
The way to tell an over rich condition is to check the plugs. There will always be a good dose of soot on them if you land immediately. The fuel flow and pressure tests will show a rich condition too. Generally an over rich condition makes the engine sluggish and you start to have problems as you pull the throttle back as the plugs have to clear themselves enough to keep the engine running.
One other problem you may have is low octane rating on the fuel. That could sure cause your engine to get rough at top end rpm.
Noel
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Peter Harris
Sent: Tuesday, January 13, 2009 2:51 AM
To: jabiruengine-list(at)matronics.com
Subject: RE: JabiruEngine-List: 3300A - Full Throttle Roughness
It sounds like it may be too rich under the load conditions at WOT cruise.
The fuel bowl is fitted with 2.25mm needle valve seat which is meant for gravity feed, but they have selected the power needle as a compromise. If you are using a fuel pump it may cause the needle valve seat to leak and overfill the fuel bowl causing excessive rich mixture near max rpm.
Another cause of over rich mixture is due to the starting choke not fully closing due to friction in the cable.
Peter
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Don Honabach
Sent: Tuesday, 13 January 2009 4:03 PM
To: jabiruengine-list(at)matronics.com
Subject: 3300A - Full Throttle Roughness
I'm having an issue where during cruise flight if I go full throttle either in straight and level or climb, the engine gets rough enough that it feels like it will quit. At this point, I obviously don't want to push the issue so I pull back on the throttle until the roughness goes away.
Interestingly, I have no problem with full throttle roughness on take-off/climb-out.
I also did some additional testing today and found that if I ease real slow into full throttle from cruise that I still get the roughness but not as bad and that the RPM will increase up to ~2,9xx and then start to degrade as I continue to add power along with additional roughness.
Background info:
Full Throttle Static RPM/Ground Run Up is ~2,800RPM. No issues with roughness.
On my 601HDS, I have a 3300A with the Sensenich Carbon Prop (64"? 2A0J5R64Z-N) that was purchased from Jabiru USA/Pete K. back in 2006.
Any help greatly appreciated. I've sent this same question to Jabiru USA and haven't gotten a response yet (sent last Thursday and sent another today asking for status).
Initially thought it was the SCAT intake hose which I replaced with the rubber 90 degree elbow. Same issue with either intake method.
Thanks!
Don Honabach
Tempe, AZ
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Lynn Matteson
Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan
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| Posted: Tue Jan 13, 2009 2:30 pm Post subject: 3300A - Full Throttle Roughness |
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I wonder why the Bing folks here in Kansas, I think it is,
recommended a 3.7 mm when I queried them about the gravity feed?
(Granted, they are not the engineers that you spoke with.) Mine has
worked really well since I went that route, which is not to say that
it wouldn't work better with the 2.25. When I had the 1.5 mm in
there, and pointed the nose up, in 10-15 seconds the thing would
starve for fuel...pointing it down cured the starvation. That was
with gravity feed. So I installed the recommended 3.7 mm, flow tested
it, (catching the fuel as it ran right through the needle seat) and
it would flow something like 13.5 gallons per hour, as I recall. I'm
wondering if there would be any benefit to switching to the 2.25mm
seat? It seems like too small is definitely bad, but too large I
cannot see as a problem...do you?
I've seen the effects that the rotation of the carb can have on the
EGT's, and I've even thought of "sharpening" that central vane, but
figured maybe Jab knew what they were doing leaving it rounded on the
leading edge....thoughts?
My air tube connection to the carb is a fiberglass 90 degree elbow
with vanes inside to separate the flow into 4 equal (I hope)
quadrants. This elbow allows the air to flow from straight above and
behind the carb. I couldn't see much difference after I installed the
vanes as opposed to having just the plain fiberglass tube. I used
the exact same tube, slicing it vertically, and installing the thin
fiberglass vanes...pics available if you'd like...then reassembling.
How's that FI coming, of is it done?
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062, 600.2 hrs
Sensenich 62x46
flying again after engine rebuild, and new Electroair direct-fire
ignition system;
also building a new pair of snow skis
On Jan 13, 2009, at 4:03 PM, Peter Harris wrote:
[quote]
<peterjfharris(at)bigpond.com>
Lynn
According to the advice I got from the German Bing website engineer
The float valve needle seat for gravity feed is 2.25 and for pump
feed is
1.5mm. I tried the 1,5mm seat and found it very I would say too
lean at
cruise because Jab has selected the power needle using the 2.25
seat/pump
combination tuned for economy cruise.
I conducted bench tests of the induction collector using a pressure
spray
gun and found that the alignment of the intake is absolutely
critical due to
the fact that inside the collector is a central vane. Any
misalignment of
the carb butterfly or of the carb on the hose attachment will cause
the
charge to favour one side or the other. If the distribution of the
charge is
bad the engine begins to "box" with uneven power strokes causing
vibration
(which I think may contribute to the flywheel bolts breakage). In
an extreme
case the engine may run bad rough.
Likewise poor scat hose configuration could contribute to the issue
and the
effect is suddenly greatest at or near WOT.
Peter
--
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azevedoflyer(at)gmail.com
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| Posted: Tue Jan 13, 2009 4:33 pm Post subject: 3300A - Full Throttle Roughness |
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Don,
Maybe your air intake system is acting - or is designed to act - as a ram charged?
Contrary to what was stated before, you might be running LEAN, because your jetting cannot compensate for additional air mass rammed in during cruise.
Failing that, check any and all rubber sleeves you might have in your intake manifold. Just one allowing "false" air into the intake tube will make your engine rattle and shake in a frightening manner!
Miguel Azevedo
N8714D
PA22/20-150
On Tue, Jan 13, 2009 at 1:03 AM, Don Honabach <don.honabach(at)pcperfect.com (don.honabach(at)pcperfect.com)> wrote:
[quote]
I'm having an issue where during cruise flight if I go full throttle either in straight and level or climb, the engine gets rough enough that it feels like it will quit. At this point, I obviously don't want to push the issue so I pull back on the throttle until the roughness goes away.
Interestingly, I have no problem with full throttle roughness on take-off/climb-out.
I also did some additional testing today and found that if I ease real slow into full throttle from cruise that I still get the roughness but not as bad and that the RPM will increase up to ~2,9xx and then start to degrade as I continue to add power along with additional roughness.
Background info:
Full Throttle Static RPM/Ground Run Up is ~2,800RPM. No issues with roughness.
On my 601HDS, I have a 3300A with the Sensenich Carbon Prop (64"? 2A0J5R64Z-N) that was purchased from Jabiru USA/Pete K. back in 2006.
Any help greatly appreciated. I've sent this same question to Jabiru USA and haven't gotten a response yet (sent last Thursday and sent another today asking for status).
Initially thought it was the SCAT intake hose which I replaced with the rubber 90 degree elbow. Same issue with either intake method.
Thanks!
Don Honabach
Tempe, AZ
[b]
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Peter H
Joined: 20 Mar 2007
Posts: 197
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| Posted: Tue Jan 13, 2009 8:40 pm Post subject: 3300A - Full Throttle Roughness |
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Lynn I think your 3.7mm seat should be fine with gravity feed. I found
removal of the 2.25 seat and fitting the 1.5 seat made a very big difference
to mixture at the higher throttle settings using the mech pump. Remove and
refit was not easy, I made a screw puller and heated the carb to about
80degC. The seat is a tight interference fit.
I am continuing with the fuel injection twin injector throttle body. At this
stage no additional power but total control of mixture. I think the power
output is limited by restricted flow through the Jab induction collector,
but had problems using a tapered plenum due to the effect near WOT when most
of the charge is delivered to the end into #1 and 2. I may spend some time
building a bottom feed plenum later.
I get very little increase in power over the last inch of throttle, do you
also?
I am also using a Navman fuel flow indicator and find it one of the most
useful instruments especially for cross country when you can adjust throttle
to get the desired fuel flow rate and also read fuel remaining accurate to
2%.
Peter
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