---------------------------------------------------------- JabiruEngine-List Digest Archive --- Total Messages Posted Sat 03/12/11: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:18 PM - Radiator Hose for Intake and 1,3,5 lean (MHerder) 2. 06:47 PM - Re: Radiator Hose for Intake and 1,3,5 lean (Martin Hone) 3. 07:22 PM - Re: Radiator Hose for Intake and 1,3,5 lean (Lynn Matteson) 4. 09:56 PM - Re: Radiator Hose for Intake and 1,3,5 lean (ple190) ________________________________ Message 1 _____________________________________ Time: 01:18:43 PM PST US Subject: JabiruEngine-List: Radiator Hose for Intake and 1,3,5 lean From: "MHerder" Hey guys, Scenario: Jab 3300, wood 64x47 Zodiac 601 HD. Recently rejetted from a .255 to .250 b/c I was running rich at high end. Flew it for about 5-10 hrs with the .250 in it, all was good, left bank was a little on the lean side and I was getting about 3100 rpm level at cruise on a good day. Decided last night to try to remove the scat hose from intake and replace with smooth lined radiator hose 2 1/8" diameter, and nice smooth molded 90 degree bend from airbox. I had expectations that I would get more power, and more even distribution of fuel, the exact opposite happened. One bank is now running even leaner, and much to my supprise I was lucky to get 2850 rpm today. I'm kind of bummed about this. What gives? My thoughts are that now that I'm getting more air to the engine, maybe my mixture might actually be too lean. But the reality is I have one rich bank and one low bank with egts ranging from 1080-1150 on 1,3,5 to 13-1350 on 2,4,6. The average of them is about right, but there is a pretty big desparity. As a side note everything is very happy and even at cruise 2200-2500. The measurements I'm giving are MWOT, which is really where I want to dial it in and get the most pwr. It seems what I really need is better and more distribution of the fuel/air I am sending into the manifold, not necissarily more or less fuel. So I've changed back to the .255 main. I did one high speed taxi like this but it was too windy to fly so I didn't get any good data. WHAT ELSE COULD IT BE. Anyone else switch to a smooth intake hose and have to readjust? -------- One Rivet at a Time! Read this topic online here: http://forums.matronics.com/viewtopic.php?p=333642#333642 ________________________________ Message 2 _____________________________________ Time: 06:47:03 PM PST US Subject: Re: JabiruEngine-List: Radiator Hose for Intake and 1,3,5 lean From: Martin Hone Hi Michael, Sounds like you have made a pretty poor situation worse, The plenum design on the 3.3 is the cause of a lot of mixture related issues. I know of some that have had some success by simply rotating the carb a few degrees while others have designed and built their own plenum and intake runners.. There is also a mod that removes the flow divider in the plenum and replaces it with a half inch round tube. But you only have to look and see the different inlet runner lengths to see part of the problem. I know that Rotec have designed a plenum and intake runner system that mates to its TBI, that replicates something you would find on a Lycoming. Obviously your smooth intake mod has upset the flow going into the carb and probably biased the fuel spray pattern to one side. You could try twisting the carb slightly so that the fuel leaving the needle jet is aimed more to the lean bank of cylinders..... Martin On Sun, Mar 13, 2011 at 7:15 AM, MHerder wrote: > michaelherder@beckgroup.com> > > Hey guys, > > Scenario: > Jab 3300, wood 64x47 Zodiac 601 HD. > > Recently rejetted from a .255 to .250 b/c I was running rich at high end. > > Flew it for about 5-10 hrs with the .250 in it, all was good, left bank was > a little on the lean side and I was getting about 3100 rpm level at cruise > on a good day. > > > Decided last night to try to remove the scat hose from intake and replace > with smooth lined radiator hose 2 1/8" diameter, and nice smooth molded 90 > degree bend from airbox. > > I had expectations that I would get more power, and more even distribution > of fuel, the exact opposite happened. One bank is now running even leaner, > and much to my supprise I was lucky to get 2850 rpm today. I'm kind of > bummed about this. What gives? > > My thoughts are that now that I'm getting more air to the engine, maybe my > mixture might actually be too lean. But the reality is I have one rich > bank and one low bank with egts ranging from 1080-1150 on 1,3,5 to 13-1350 > on 2,4,6. The average of them is about right, but there is a pretty big > desparity. As a side note everything is very happy and even at cruise > 2200-2500. The measurements I'm giving are MWOT, which is really where I > want to dial it in and get the most pwr. It seems what I really need is > better and more distribution of the fuel/air I am sending into the manifold, > not necissarily more or less fuel. > > So I've changed back to the .255 main. I did one high speed taxi like > this but it was too windy to fly so I didn't get any good data. > > WHAT ELSE COULD IT BE. Anyone else switch to a smooth intake hose and have > to readjust? > > -------- > One Rivet at a Time! > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=333642#333642 > > ________________________________ Message 3 _____________________________________ Time: 07:22:33 PM PST US From: Lynn Matteson Subject: Re: JabiruEngine-List: Radiator Hose for Intake and 1,3,5 lean Michael- First off, if 1,3, and 5 are 1080-1150, that's NOT lean, that's rich. The 2,4, and 6 at 13-1350 is on the lean side....unless it is late, and my brain is fried. To further explain what Martin is saying...imagine that the spray of fuel leaving the carb is positioned at the 6 o'clock position inside the carb (it is, actually). If the lean bank is 2,4, and 6, you need to rotate the carb bottom so that the 6 o'clock moves toward the 2,4,6 bank of cylinders....this would be toward the 7 o'clock position in your 601/ tractor installation. This rotation will make the fuel discharge go on the left side of the flow divider, richening the left bank of cylinders...the 2,4,6 side. When I was running a Bing, I made a small pointer that I affixed near the carb and then made a scratch on the carb so I would have a starting point and could always return there if I needed to. Be aware that it doesn't take much of a twist of the carb to make a big difference. Further, is that 90 degree bend a vertical bend? According to the wisdom (?) of about 5 years ago, the Bing likes to get its air from above or below the carb and not coming in from the side. If your new smooth hose comes to the carb from the side, that alone might have caused the problem you are now having. Lynn Matteson Kitfox IV Speedster, taildragger Jabiru 2200, #2062 Prince prop (64 x 30, P-tip) Electroair direct-fire ignition system Rotec TBI-40 injection (sleeved to 35mm) Status: flying...1086 hrs (since 3-27-2006) On Mar 12, 2011, at 9:43 PM, Martin Hone wrote: > Hi Michael, > > Sounds like you have made a pretty poor situation worse, The > plenum design on the 3.3 is the cause of a lot of mixture related > issues. I know of some that have had some success by simply > rotating the carb a few degrees while others have designed and > built their own plenum and intake runners.. There is also a mod > that removes the flow divider in the plenum and replaces it with a > half inch round tube. But you only have to look and see the > different inlet runner lengths to see part of the problem. I know > that Rotec have designed a plenum and intake runner system that > mates to its TBI, that replicates something you would find on a > Lycoming. > Obviously your smooth intake mod has upset the flow going into the > carb and probably biased the fuel spray pattern to one side. You > could try twisting the carb slightly so that the fuel leaving the > needle jet is aimed more to the lean bank of cylinders..... > > Martin > > On Sun, Mar 13, 2011 at 7:15 AM, MHerder > wrote: > > > Hey guys, > > Scenario: > Jab 3300, wood 64x47 Zodiac 601 HD. > > Recently rejetted from a .255 to .250 b/c I was running rich at > high end. > > Flew it for about 5-10 hrs with the .250 in it, all was good, left > bank was a little on the lean side and I was getting about 3100 rpm > level at cruise on a good day. > > > Decided last night to try to remove the scat hose from intake and > replace with smooth lined radiator hose 2 1/8" diameter, and nice > smooth molded 90 degree bend from airbox. > > I had expectations that I would get more power, and more even > distribution of fuel, the exact opposite happened. One bank is now > running even leaner, and much to my supprise I was lucky to get > 2850 rpm today. I'm kind of bummed about this. What gives? > > My thoughts are that now that I'm getting more air to the engine, > maybe my mixture might actually be too lean. But the reality is I > have one rich bank and one low bank with egts ranging from > 1080-1150 on 1,3,5 to 13-1350 on 2,4,6. The average of them is > about right, but there is a pretty big desparity. As a side note > everything is very happy and even at cruise 2200-2500. The > measurements I'm giving are MWOT, which is really where I want to > dial it in and get the most pwr. It seems what I really need is > better and more distribution of the fuel/air I am sending into the > manifold, not necissarily more or less fuel. > > So I've changed back to the .255 main. I did one high speed taxi > like this but it was too windy to fly so I didn't get any good data. > > WHAT ELSE COULD IT BE. Anyone else switch to a smooth intake hose > and have to readjust? > > -------- > One Rivet at a Time! > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=333642#333642 > > > ========== > -List" target="_blank">http://www.matronics.com/Navigator? > JabiruEngine-List > ========== > http://forums.matronics.com > ========== > le, List Admin. > ="_blank">http://www.matronics.com/contribution > ========== > > > www.matronics.com/contribution _- > =========================================================== ________________________________ Message 4 _____________________________________ Time: 09:56:40 PM PST US Subject: JabiruEngine-List: Re: Radiator Hose for Intake and 1,3,5 lean From: "ple190" Have you tried a cross insert in the airbox outlet pipe, this has helped a lot of people even out their EGT's. Just epoxy in some .5mm Al or use thin glass Read this topic online here: http://forums.matronics.com/viewtopic.php?p=333697#333697 Attachments: http://forums.matronics.com//files/gedc1043_106.jpg ------------------------------------------------------------------------------------- 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.