---------------------------------------------------------- TeamGrumman-List Digest Archive --- Total Messages Posted Mon 11/28/05: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:10 AM - Please Read - Who is "Matt Dralle" and What are "The Lists"...? (Matt Dralle) 2. 10:03 AM - Re: AOPA Tiger article (TeamGrumman@aol.com) 3. 10:27 AM - Manifold Pressure (linn walters) 4. 12:50 PM - Re: manifold pressure (linn walters) 5. 06:12 PM - Re: Manifold Pressure (TeamGrumman@AOL.COM) 6. 06:24 PM - Re: Re: manifold pressure (TeamGrumman@AOL.COM) 7. 07:05 PM - Re: Manifold Pressure (linn walters) 8. 07:27 PM - Re: Re: manifold pressure (linn walters) 9. 11:51 PM - Re: Re: manifold pressure (TeamGrumman@AOL.COM) ________________________________ Message 1 _____________________________________ Time: 12:10:28 AM PST US From: Matt Dralle Subject: TeamGrumman-List: Please Read - Who is "Matt Dralle" and What are "The Lists"...? --> TeamGrumman-List message posted by: Matt Dralle Dear Listers, Who is Matt Dralle and what exactly are these Lists? Well, I've been working in the information technology industry for over 20 years primarily in computer networking design and implementation. I've also had a rather extensive background in web development and CGI design during this period. I started the Matronics Email Lists back in 1990 with about 30 fellow RV builders from around the world. Since that time, I have added 50 other kinds of aircraft related Lists to the line up and numerous other List related services such as the Archives and Search Engine just to name a few. For the upmost in flexibility and reliability, I have chosen to run all of my own servers here locally. Other support systems include a 1 Gigabit, fully switched network infrastructure, a commercial-grade Netscreen firewall, a Barracuda spam filter, a local T1 Internet router, and a commercial business T1 Internet connection with static addressing. The computer servers found here include two, dual processor Xeon Linux systems dedicated to the email and web functions respectfully, and another P4 Linux system serving as a remote storage disk farm for the archives, databases, and for an on-line, hard drive-based backup system with 3.2 Terabytes of storage. This entire system is protected by multiple commercial-grade uninterrupted power supply (UPS) systems that assure the Lists are available even during a local power outage! I recently upgraded all of the computer racking infrastructure including new power feeds and dedicated air conditioning for the room that serves as the Computer Center for the Matronics Email Lists. Here's a new composite photo of the List Computer Center following this Summer's upgrades! http://www.matronics.com/MattDralle-ListComputerCenter.jpg As you can see, I take running these Lists very seriously and I am dedicated to providing an always-on, 24x7x365 experience for each and every Lister. But building and running this system isn't cheap. As I've stated before, I don't support any of these systems with commercial advertising on the Lists. It is supported 100% through List member Contributions! That means you... and you... and YOU! To that end, I hold a List Fund Raiser each November and ask that members make a small Contribution to support the continued operation and upgrade of this ever-expanding system. Its solely YOUR Contributions that keep it running! Please make a Contribution today to support these Lists! http://www.matronics.com/contribution Thank you! Matt Dralle Matronics Email List Administrator Matt G Dralle | Matronics | PO Box 347 | Livermore | CA | 94551 925-606-1001 V | 925-606-6281 F | dralle@matronics.com Email http://www.matronics.com/ WWW | Featuring Products For Aircraft do not archive ________________________________ Message 2 _____________________________________ Time: 10:03:31 AM PST US From: TeamGrumman@aol.com Subject: Re: TeamGrumman-List: AOPA Tiger article --> TeamGrumman-List message posted by: TeamGrumman@aol.com In a message dated 11/28/05 7:13:29 AM, Douglas.Weir@us.calyon.com writes: > Gary, > Did you also install the PowerFlow exhaust on your plane?=A0 Are you a > believer? > > Oh, yes, I forgot to say that. It does have the short stack Power Flow. The power Flow exhaust system is very well designed right up to where they attach the muffler to the plane. On the original setup, the muffler would=20hang loosely and wobble back and forth. On the short stack, the support brace is at such a poor angle that it is useless. We had a new 182 Cessna do a hard landing here. When the cowling was off,=20I noticed the muffler supported by a bracket mounted to the firewall. Clearly a lot better way to support the muffler. SOOOOO, I mounted my short stack so that the muffler has a descent support at the firewall. Other-than-that, anything beats the poorly designed stock muffler. If I could replace every stock muffler with the power flow, I would. By-the-way, I got an additional 80 rpm at 12,500 feet with the power flow. =20 At 17,500 feet, I can still turn it 2650 rpm. Gary ________________________________ Message 3 _____________________________________ Time: 10:27:38 AM PST US From: linn walters Subject: TeamGrumman-List: Manifold Pressure --> TeamGrumman-List message posted by: linn walters I sent this to the Grumman Gang also so I apologize for the duplicate posts!!! I'm helping troubleshoot a 'burping' problem in an O-360. Yesterday, on our flight in search of food, I took some data. We set the throttle near 2300 at full rich. I only changed the mixture two turns at a time and recorded RPM, Man Press, Fuel Flow and EGTs. Remember, the only change was in mixture. What surprised me was the change in MP. It changed from 21.7 to 22.5 from full rich to full lean. I don't understand, so hopefully someone can tell me why it changed. The burps start at around 10 turns from full rich with MP @ 22.0, FF at 8.2 GPH, RPM at 2320, and EGTs of 1407,1450, 1413, and 1364 (cyls 1-4) The burps are significant, absent at full rich, and getting worse as the engine is leaned. They're also not regular in frequency. The engine does experience normal roughness when leaned too much, and is different than the burps. The burps would be about the same intensity as total ignition failure for a fraction of a second, and occur anywhere from infrequent at richer settings to every 15 seconds at leaner settings. Help me out here guys. I haven't a clue what's going on. Mags are new, carb overhauled, new plugs and harness. What should I look at next??? Linn do not archive -- ________________________________ Message 4 _____________________________________ Time: 12:50:05 PM PST US From: linn walters Subject: TeamGrumman-List: Re: manifold pressure --> TeamGrumman-List message posted by: linn walters Ron Levy wrote: >>It's a FP prop. This plane has an engine analyzer installed and that's >>where the data came from. >> >> >[Levy] OK, then what did the RPM do when the MP went up, or did you throttle >back to keep the 2300 RPM? Or was all this leaning done at full throttle? > >Ron > The RPM changed with leaning ...... and the pilots inability to hold altitude really well ......and the throttle wasn't full. I don't have much experience with MP, and was under the impression that it was controlled solely by throttle, and that once the throttle was set, so was the MP. I appreciate the input from Bob, Craig and Ron. I'm learning!!! So, back to the burping (term changed for the family-type email list :-) ) that we're experiencing. Throughout the leaning process, #3 was the coolest, #1 and #4 we're roughly parallel, but #2, which started with a delta of 25 below #4 (1230 Vs 1270) crossed #4 at 1375 and peaked 20 degrees higher (#2 @1465 and #4 @ 1445) Peak for all 4 were at: 1 1425 2 1465 3 1400 4 1445 If that means anything!!! When the burps start, the EGTs were: 1 1405 2 1450 3 1370 4 1415 Like I said, these burps are severe ...... like it took a slug of water (none found anywhere) or the ignition shut down. Only for a heartbeat ..... which causes heartrate rise in the pilot/owner. Open to any sugestions. Craig mentioned intake leaks .... but they've done the pressure/soapy water thingy already with no apparent leaks. We might do that again when the cowl is off next time. All the normal things (ignition, timing, air intake ...... all have been looked at and this is a recent rebuild. Time to think out of the box, I guess. Linn ________________________________ Message 5 _____________________________________ Time: 06:12:20 PM PST US From: TeamGrumman@AOL.COM Subject: Re: TeamGrumman-List: Manifold Pressure --> TeamGrumman-List message posted by: TeamGrumman@aol.com Right after dubya-dubya 2, we'd set the idle on our Model-T hot rods using a vacuum gage. I can talk like that now; I'm going to be a great-grandpa. Seriously, we would set the timing and the idle mixture to maximum manifold vacuum. That's minimum manifold pressure. - - - at what altitude was this? Now, all that's all well and good, but, increasing the manifold pressure by leaning, that's a new one. I HAVE noticed a change in manifold pressure, running straight and level, due to outside pressure changes. Just a thought. As for the burping, are you certain you aren't leaning to the point of misfire? I know that you said it's different than a lean misfire. Just checking. OK, that said, .... on two separate occasions, I experienced this exact same burping in my Cheetah. I always leaned to near mis-fire. I attributed the 'burping' to the 1-piece venturi. The 'burping' happened right after the change. I know that isn't the problem with your O-360 unless you have an updraft carb. What I did, was put on new mags, a new harness and get the perforated main-jet nozzle for the carb. I never experienced the misfire after that. Now, I know I don't need to ask, but I will. What does your JPI 700/800 tell you? Which cylinder is missing? When you download the data stream, and look over the data, what are the EGTs doing when the burping occurs? With a JPI 800, I know you have manifold pressure and RPM also being recorded. What do they say? WHAT? You don't have a JPI? I can get a good discount on one for you. I would still try different mags. Do you have a Slick ignition harness? I like them better than the cheaper ones. Still, if you have an engine analyzer, it will tell you if it's one cylinder or all of them. Gary ________________________________ Message 6 _____________________________________ Time: 06:24:35 PM PST US From: TeamGrumman@AOL.COM Subject: Re: TeamGrumman-List: Re: manifold pressure --> TeamGrumman-List message posted by: TeamGrumman@aol.com Linn, Based on the drop in EGT, I'd agree the entire system is shutting down for a second. How long is the drop on the data? Also, does the EGT go back up when it wakes up again? Disconnect the P-leads and try it. Maybe you have a shorted P-lead. Gary ________________________________ Message 7 _____________________________________ Time: 07:05:40 PM PST US From: linn walters Subject: Re: TeamGrumman-List: Manifold Pressure --> TeamGrumman-List message posted by: linn walters TeamGrumman@aol.com wrote: >--> TeamGrumman-List message posted by: TeamGrumman@aol.com > >Right after dubya-dubya 2, we'd set the idle on our Model-T hot rods using a >vacuum gage. I can talk like that now; I'm going to be a great-grandpa. > >Seriously, we would set the timing and the idle mixture to maximum manifold >vacuum. > > > That's minimum manifold pressure. > > - - - at what altitude was this? > >Now, all that's all well and good, but, increasing the manifold pressure by >leaning, that's a new one. I HAVE noticed a change in manifold pressure, >running straight and level, due to outside pressure changes. Just a thought. > This was definitely caused by leaning. >As for the burping, are you certain you aren't leaning to the point of >misfire? I know that you said it's different than a lean misfire. Just checking. > The burping starts at 10 turns of the mixture. No, it's not calibrated! Lean is at 11 turns to 12. The EGTs rise 20 to 30 points(depending on which cylinder you look at) from burping to 'too lean' roughness. >OK, that said, .... on two separate occasions, I experienced this exact same >burping in my Cheetah. I always leaned to near mis-fire. I attributed the >'burping' to the 1-piece venturi. The 'burping' happened right after the >change. I know that isn't the problem with your O-360 unless you have an >updraft carb. > Hee, Hee, we do!!! >What I did, was put on new mags, a new harness and get the perforated >main-jet nozzle for the carb. I never experienced the misfire after that. > Do you think it was the main jet nozzle change that did the trick? That hasn't been done yet. Don't know which venturi is in the carb either. I'll ask. >Now, I know I don't need to ask, but I will. What does your JPI 700/800 >tell you? Which cylinder is missing? When you download the data stream, and >look over the data, what are the EGTs doing when the burping occurs? With a >JPI 800, I know you have manifold pressure and RPM also being recorded. What >do they say? > >WHAT? You don't have a JPI? I can get a good discount on one for you. > I think this one is an EI, but not sure. I'll check. It would be really nice to be able to download the info and graph it on the computer instead of a quadrille pad!!! >I would still try different mags. > They've used 'borrowed' mags and new ones with new harness. > Do you have a Slick ignition harness? > Not sure about the ignition/harness maker. I'll check that too. > >I like them better than the cheaper ones. Still, if you have an engine >analyzer, it will tell you if it's one cylinder or all of them. > The burp is so short that it doesn't make any difference in the 1-3 points that the EGTs vary when not burping. I didn't check whether one mag or the other made the problem worse or go away. That's for a later flight. Thanks for the comments. The carb jet change may be the ticket. Linn do not archive > >Gary > > > > > -- ________________________________ Message 8 _____________________________________ Time: 07:27:03 PM PST US From: linn walters Subject: Re: TeamGrumman-List: Re: manifold pressure --> TeamGrumman-List message posted by: linn walters Whoa. I may have mis-typed!!! There is no drop in EGTs when the burps occur. The engine monitor will float +/- a couple of points when it's not burping so it's really hard to see the burp on the EGTs. Linn do not archive TeamGrumman@AOL.COM wrote: >--> TeamGrumman-List message posted by: TeamGrumman@aol.com > >Linn, > >Based on the drop in EGT, I'd agree the entire system is shutting down for a >second. How long is the drop on the data? Also, does the EGT go back up >when it wakes up again? > >Disconnect the P-leads and try it. Maybe you have a shorted P-lead. > >Gary > > > > -- ________________________________ Message 9 _____________________________________ Time: 11:51:44 PM PST US From: TeamGrumman@AOL.COM Subject: Re: TeamGrumman-List: Re: manifold pressure --> TeamGrumman-List message posted by: TeamGrumman@aol.com It looks to me like the EGTs were 15 to 30 degrees lower. > Whoa.=A0 I may have mis-typed!!!=A0 There is no drop in EGTs when the burps > occur.=A0 The engine monitor will float +/- a couple of points when it's > not burping so it's really hard to see the burp on the EGTs. > Peak for all 4 were at: 1=A0=A0 1425 2=A0=A0 1465 3=A0=A0 1400 4=A0=A0 1445 If that means anything!!! When the burps start, the EGTs were: 1=A0=A0 1405 2=A0=A0 1450 3=A0=A0 1370 4=A0=A0 1415