---------------------------------------------------------- JabiruEngine-List Digest Archive --- Total Messages Posted Fri 11/02/07: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:20 AM - Re: Carb jet changes () 2. 11:34 AM - Re: Carb jet changes (Lynn Matteson) 3. 02:37 PM - Fuel Type (Ernie Rairdin) ________________________________ Message 1 _____________________________________ Time: 06:20:23 AM PST US From: Subject: RE: JabiruEngine-List: Carb jet changes Actually, according to Pete Krotje, rotating the top of the carb toward the cool side works because it moves the jet, which is on the bottom of the carb throat, toward the hot side. The Bottom of the intake stream where the jet is spewing fuel, tends to be the richer area in the intake stream going inmto the plenum. Moving that rich segment of the intake flow to the hot (lean) side richens the mixture for the cylinders on that side. At least that's what I was taught. Dred ---- Peter Harris wrote: > > Lynn > By TBI I mean throttle body fuel injection. I have a 45mm throttle body with > two injectors. > Rotating the carb. means that the partly opened butterfly is directing the > air/fuel flow to one side or the other and this affects mixture rich or lean > each side of the plenum. > With the throttle body I have it mounted so the butterfly axis is horizontal > and the problem does not arise. > Peter H > > -----Original Message----- > From: owner-jabiruengine-list-server@matronics.com > [mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of Lynn > Matteson > Sent: Friday, 2 November 2007 11:49 AM > To: jabiruengine-list@matronics.com > Subject: Re: JabiruEngine-List: Carb jet changes > > > Hi Peter- > I have an electric boost pump, but only use it to insure fuel at the > carb after any work done, or to check for carb leakage, like I found > this week. A test pilot turned it on while landing a year ago (not > knowing any better) and the engine quit. Without the electric pump, > and with only the mechanical Jabiru pump operating while engine is > running, the gauge reads 2 lbs. pressure, and all seems to be fine. > > I should note that when I first got the plane up after the changes, > it was running hotter on the right-hand 2 cylinders. I rotated the > carb according to the "old wives tale", that is rotate the top of the > carb towards the cool, rich side, and that helped. I then rotated it > again, a little more this time, and the cylinders are within 60-70 F > of one another, for most of the operating range...certainly where it > operates the most, at cruising speed. Having had the plenum chamber > and carb off last week I can see how this works. If the carb is > rotated, the spray pattern will change in respect to the divider that > is situated inside the plenum chamber. Apparently if the carb top is > rotated towards the cool side, the spray pattern is divided more > toward the hot, lean side, and the temps between the two sides become > closer together. At least that's what I've been able to observe. > > It's late at night and my memory is fading...what's TBI? A type of > carb, I'm assuming? I'm just not recalling.... > > Lynn Matteson > Grass Lake, Michigan > Kitfox IV Speedster w/Jabiru 2200 > flying w/420+ hrs > > > > > > On Nov 1, 2007, at 9:01 PM, Peter Harris wrote: > > > > > > > Lynn > > I found with the J3300 that the needle seat supplied is 2.25mm and > > according > > to Bing engineers is meant for gravity feed. Anything above 2500RPM > > and it > > ran over rich. > > I replaced that seat with the 1.5mm seat recommended by Bing and > > that cured > > rich running all the way to WOT and EGT was within recommended range > > although hotter, but if I turned on the electric boost pump even > > this 1.5mm > > seat leaked and caused a big increase in fuel consumption. I > > discussed with > > Jabiru engineers and they confirmed policy to run with the over > > size seat to > > cool the engine and it "works" OK up to 2700 RPM and is "safe" > > above that > > with consumption up to 40LPH. > > I am now using TBI and have total control of mixture full range. > > Peter H > > > > -----Original Message----- > > From: owner-jabiruengine-list-server@matronics.com > > [mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of > > Lynn > > Matteson > > Sent: Friday, 2 November 2007 7:09 AM > > To: jabiruengine-list@matronics.com > > Subject: JabiruEngine-List: Carb jet changes > > > > > > > > I had an interesting week working on the Bing carb on my serial #2062 > > Jabiru 2200A engine. I had been running the engine with the cowl off, > > and I noticed that fuel was going up the clear tube that is the carb > > bowl vent. I assumed that this was a temporary overflow of fuel and > > it would soon be gone with the engine running, but it was not. > > However, revving the engine got rid of the fuel in that line. > > Finally, I closed the main fuel valve, and shut the engine off. I > > then took the incoming air hose off the carb, and about a half-cup of > > fuel gushed out. This led me to believe that the float needle was > > leaking...DUH! It turned out to be exactly that. I ordered a new > > needle and seat, and a #40 idle jet. The reason for ordering the jet > > was I had read others' comments that the #40 jet took care of their > > idling problems. With the new needle and seat in place, and #40 jet > > too, the engine ran great, and I could get the idle down to below > > 900, and it was smooth. Later on, I decide to test the old #45 jet, > > so I reinstalled it, and the engine ran great with that (original) > > jet. So my major problem was with the float needle and seat, and > > nothing else. Amazingly, I have had this bad idle problem for some > > time now, and it's been a leaking needle and seat all along. I had > > been just learning to deal with the rough idle. > > > > Along with curing the rough idle, I no longer have to shut the main > > fuel valve off 30 seconds before I shut the engine down. I thought by > > doing this, I was lowering the fuel level in the float bowl, and > > thereby keeping the carb from "boiling over", but I was just using up > > the excess fuel that was already (probably) laying in the inlet air > > hose. > > > > > > Lynn Matteson > > > > > > > > > > > > > > > ________________________________ Message 2 _____________________________________ Time: 11:34:24 AM PST US From: Lynn Matteson Subject: Re: JabiruEngine-List: Carb jet changes Excellent, Dred. That's the way I had it figured out, and now that I see the divider inside the plenum, it makes more sense to me WHY the rotation of the carb works. Lynn On Nov 2, 2007, at 9:19 AM, wrote: > > Actually, according to Pete Krotje, rotating the top of the carb > toward the cool side works because it moves the jet, which is on > the bottom of the carb throat, toward the hot side. The Bottom of > the intake stream where the jet is spewing fuel, tends to be the > richer area in the intake stream going inmto the plenum. Moving > that rich segment of the intake flow to the hot (lean) side richens > the mixture for the cylinders on that side. > > At least that's what I was taught. > > Dred > > ---- Peter Harris wrote: >> >> >> Lynn >> By TBI I mean throttle body fuel injection. I have a 45mm throttle >> body with >> two injectors. >> Rotating the carb. means that the partly opened butterfly is >> directing the >> air/fuel flow to one side or the other and this affects mixture >> rich or lean >> each side of the plenum. >> With the throttle body I have it mounted so the butterfly axis is >> horizontal >> and the problem does not arise. >> Peter H >> >> -----Original Message----- >> From: owner-jabiruengine-list-server@matronics.com >> [mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of >> Lynn >> Matteson >> Sent: Friday, 2 November 2007 11:49 AM >> To: jabiruengine-list@matronics.com >> Subject: Re: JabiruEngine-List: Carb jet changes >> >> >> >> Hi Peter- >> I have an electric boost pump, but only use it to insure fuel at the >> carb after any work done, or to check for carb leakage, like I found >> this week. A test pilot turned it on while landing a year ago (not >> knowing any better) and the engine quit. Without the electric pump, >> and with only the mechanical Jabiru pump operating while engine is >> running, the gauge reads 2 lbs. pressure, and all seems to be fine. >> >> I should note that when I first got the plane up after the changes, >> it was running hotter on the right-hand 2 cylinders. I rotated the >> carb according to the "old wives tale", that is rotate the top of the >> carb towards the cool, rich side, and that helped. I then rotated it >> again, a little more this time, and the cylinders are within 60-70 F >> of one another, for most of the operating range...certainly where it >> operates the most, at cruising speed. Having had the plenum chamber >> and carb off last week I can see how this works. If the carb is >> rotated, the spray pattern will change in respect to the divider that >> is situated inside the plenum chamber. Apparently if the carb top is >> rotated towards the cool side, the spray pattern is divided more >> toward the hot, lean side, and the temps between the two sides become >> closer together. At least that's what I've been able to observe. >> >> It's late at night and my memory is fading...what's TBI? A type of >> carb, I'm assuming? I'm just not recalling.... >> >> Lynn Matteson >> Grass Lake, Michigan >> Kitfox IV Speedster w/Jabiru 2200 >> flying w/420+ hrs >> >> >> >> >> >> On Nov 1, 2007, at 9:01 PM, Peter Harris wrote: >> >>> >>> >>> Lynn >>> I found with the J3300 that the needle seat supplied is 2.25mm and >>> according >>> to Bing engineers is meant for gravity feed. Anything above 2500RPM >>> and it >>> ran over rich. >>> I replaced that seat with the 1.5mm seat recommended by Bing and >>> that cured >>> rich running all the way to WOT and EGT was within recommended range >>> although hotter, but if I turned on the electric boost pump even >>> this 1.5mm >>> seat leaked and caused a big increase in fuel consumption. I >>> discussed with >>> Jabiru engineers and they confirmed policy to run with the over >>> size seat to >>> cool the engine and it "works" OK up to 2700 RPM and is "safe" >>> above that >>> with consumption up to 40LPH. >>> I am now using TBI and have total control of mixture full range. >>> Peter H >>> >>> -----Original Message----- >>> From: owner-jabiruengine-list-server@matronics.com >>> [mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of >>> Lynn >>> Matteson >>> Sent: Friday, 2 November 2007 7:09 AM >>> To: jabiruengine-list@matronics.com >>> Subject: JabiruEngine-List: Carb jet changes >>> >>> >>> >>> I had an interesting week working on the Bing carb on my serial >>> #2062 >>> Jabiru 2200A engine. I had been running the engine with the cowl >>> off, >>> and I noticed that fuel was going up the clear tube that is the carb >>> bowl vent. I assumed that this was a temporary overflow of fuel and >>> it would soon be gone with the engine running, but it was not. >>> However, revving the engine got rid of the fuel in that line. >>> Finally, I closed the main fuel valve, and shut the engine off. I >>> then took the incoming air hose off the carb, and about a half- >>> cup of >>> fuel gushed out. This led me to believe that the float needle was >>> leaking...DUH! It turned out to be exactly that. I ordered a new >>> needle and seat, and a #40 idle jet. The reason for ordering the jet >>> was I had read others' comments that the #40 jet took care of their >>> idling problems. With the new needle and seat in place, and #40 jet >>> too, the engine ran great, and I could get the idle down to below >>> 900, and it was smooth. Later on, I decide to test the old #45 jet, >>> so I reinstalled it, and the engine ran great with that (original) >>> jet. So my major problem was with the float needle and seat, and >>> nothing else. Amazingly, I have had this bad idle problem for some >>> time now, and it's been a leaking needle and seat all along. I had >>> been just learning to deal with the rough idle. >>> >>> Along with curing the rough idle, I no longer have to shut the main >>> fuel valve off 30 seconds before I shut the engine down. I >>> thought by >>> doing this, I was lowering the fuel level in the float bowl, and >>> thereby keeping the carb from "boiling over", but I was just >>> using up >>> the excess fuel that was already (probably) laying in the inlet air >>> hose. >>> >>> >>> Lynn Matteson >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> > > ________________________________ Message 3 _____________________________________ Time: 02:37:53 PM PST US From: Ernie Rairdin Subject: JabiruEngine-List: Fuel Type Hi Guys The airport where our J250 is hangered now sells both 100LL and 91 Octane auto fuel. Curious what some of you use in the 3300 engine. We've been using 100LL, as that's what was available.. Ernie (still working on my license) ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message jabiruengine-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/JabiruEngine-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/jabiruengine-list Browse Digests http://www.matronics.com/digest/jabiruengine-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.