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O-320 E2D Drama

Sam I Am

Member
I purchased my first plane, a 2003 Vans RV-9A, July 2018. I commute from Texas to Kansas weekly for work so have accumulated almost 200 hours since purchase. The plane had 525 TT when I bought it. The Lycoming was a rebuilt that was in storage for some time before the RV builder purchased it in 1999. Previous log books were not available but Lycoming estimated that it had been in use for 2,000 h when he purchased it. The engine was disassembled and reassembled by A&P with new gaskets and seals at time of the builders purchase and pistons, valves, seats, cam, lifters, etc all appeared new based on log book entry. Had a prebuy conducted and no issues were noted at purchase.

Almost immediately fuel burn went to 11 to 12 g/h and the engine would not run smoothly. Two mechanics later there were multiple fuel leaks found. Replaced the Van's fuel selector valve with Andair. Fixing the leaks brought the fuel use back to 7,5 to 8 g/h but the engine was not very smooth. Found the intake connector hose clamps were loose and tightened them up. Through trial and error determined that when the electric fuel pump was turned on, the engine would turn off! Only use electric fuel pump when priming. The primer was checked and not leaking fuel to the cylinders when not activated.

High CHTS climbing out has been a common issue (425F) until fall weather brought cooler ambient temps. The plane is equiped with and EIS 2000 with probes in the 1 and 4 cylinders. Baffling is in good shape and checked again last night with flash light for leaks. Started to notice that the mixture would be set at flight elevation then would get LOP after some time. The engine tried to quit several times at take off then did quit at 11,500 over the panhandle one day. I then replaced the carb with a rebuilt Marvel-Schebler MA-4SPA and a new lycoming mechanical fuel pump. Wow! The engine ran much smoother and fuel burn at 7 g/h. Thought I had it fixed....

Now that the weather is warming up, the CHT are skyrocketing. Yesterday I left TOP (880 msl, 60 degrees F). I taxied to the runway with the engine leaned, conducted my runup to 1,800 rpm after enrichening the mixture. The left mag was rough so ran the engine up and leaned to burn off the plugs. Next mag check spot on. As I lined up to take off, the CHT #4 was already 425 F and #1 was 415F. I took off with one eye on the sky and one on the EIS. I climbed very slowly, full rich, as the temps went to 485. When I reached 3,500 msl, the cylinders started to cool to less than 400 F as I continued to climb to 10,500 (32 degrees F). The temps settled in at 375 and 355 for the remainder of the flight. When I landed in Amarillo, the temps immediately went to 285 for roll to the hangar. This has been the condition for the last 3 flights. The previous flights did not entail having to burn off the plugs before take off.

I'm about to conduct an intake leak test but thinking that my scenerio doesn't quite fit a leak. I've read that the Lycoming SB 258 can be an issue so will pull the carb and check the intake through the sump for dead space. Any other ideas would be much appreciated.

While I have the podium, I would like to thank everyone for their time and knowledge on this forum. I'm a newly minted pilot with a new plane and would have walked away by now had it not been for this forum and peoples honest input. THANK YOU!!!!
 
New spark plugs and timing was checked at annual in July 2018. Slick mags rebuilt in 2016. Good point and will check timing again.
 
Check engine baffles for leakage and or good seal. CHT on slow taxi , TO and Climb are effected tremendously by leakage and by pass. Be sure all baffles are turned to correct position after cowl installed. Poor Seals at cowl inlet { to lower section} are bypass killers.
 
I took off with one eye on the sky and one on the EIS. I climbed very slowly, full rich, as the temps went to 485.

During this climb, what was the airspeed, RPM, and fuel flow? What prop type are you running? It's possible/likely the main jet on the new carb is too small.

Larry
 
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Maybe leaks at the intake tube gaskets to the cylinders making everything too lean, regardless of mixture control?

Admittedly I'm watching this thread closely. I've had insanely high CHTs also. But for me that might be a combo of timing maps in the EFII system, using an SJ cowl, and baffles. We'll see this weekend after my 5-month winter overhaul after I switched to a factory cowl and did some timing remapping. ;)
 
Same same

I have the same setup, but had to break in engine during summer temps in souther California. After break in CHT?s were still HIGH.

Installed ANTISPLAT cowl flap and it instantly solved all problems of cooling. Just recently installed a second cowl flap ( not required ) but just for additional even cooling.

Its easy to install and worth every penny! Antisplat has great customer service and everything I purchased is of high quality,
 
Take a step back, pls

Sam:

My two cents:
1. Stop flying the airplane.
This will not fix itself. It will get worse, until you resolve underlying issues.
You can choose to fix an unflyable airplane on the ground. In the air you have fewer choices, with worse consequences.

2. Pay for an evaluation by a no-kidding RV expert, to include a thorough inspection, and if safe, a flight to evaluate operations.
Mr. Syracuse comes to my mind.

3. Don't poke holes in the airplane.
Lots of RVs fly, in hot places, without 485F temps on climbout.

R&R doesn't seem to have identified underlying issues. Remove and replace, as you're seeing, is expensive in time, money, and opportunity cost.

The good news:
-you're reading this, I hope, safely on the ground. We're not reading about you.
-this is fixable (with enough information, time, money, and effort.)

Caveats: my perspective is based on reading many Lycoming pubs, operating (1) RV-9A with an 0-320-E2D for a couple of hundred hours, and doing my own maintenance.
I'm no expert!


Good luck, and be safe.
 
I keep thinking timing as others have mentioned.

I had an O-320-E2D on my Yankee years ago, and for some reason, the flywheel was not keyed - you could put it on any way you wanted. Sure enough, it got put on one set of bolt holes off - so while it had timing marks, they were completely wrong! To make sure, when you recheck the timing, actually measure the #1 TDC position through the spark plug hole.

Probably not your case...but its one way that you THINK the timing is right, when its not....
 
Kind of agree. Sounds like they aren't present. I had some on a plane once that I tracked down to coming off an 0-290 generator. They weren't holding in the upper pressure and were just letting all of the air escape on by.

Second is same as everyone else, timing. Time to double check the old fashioned way instead of relying on timing marks as Paul pointed out. Saying you've already found issues leads me to believe the engine is cobbled together by someone with just enough knowledge to get by. It would really make me question everything else...
 
Two thoughts...

Are you throttling back after takeoff, to reduce power requirement and hopefully temperatures? If so, you're putting less cooling fuel into the system at a high-load time. At full throttle there is an enrichment circuit that opens and puts more fuel into the engine for full-throttle operation. I found leaving full throttle in the climb lowered my CHT's significantly on warm days.

Is this engine a former Cessna 172 engine? If so, it's probably jetted for operation at 172 speeds and airflows through the carb. You can tell if leaning during your runup doesn't give much, if any, RPM rise before it drops again. If this is the case, you may never be getting "full rich".
 
I keep thinking timing as others have mentioned.

I had an O-320-E2D on my Yankee years ago, and for some reason, the flywheel was not keyed - you could put it on any way you wanted. Sure enough, it got put on one set of bolt holes off - so while it had timing marks, they were completely wrong! To make sure, when you recheck the timing, actually measure the #1 TDC position through the spark plug hole.

Probably not your case...but its one way that you THINK the timing is right, when its not....

Ditto this, was doing a conditional on friends RV-6A with an 0-360. Could not get the engine timed to markings on flywheel. I notice a faint felt tip pen marking on the flywheel. Sure enough, this is what the previous owner had used for timing rather than clock the flywheel in the right place. Ya really find strange things on some of these planes.:eek:
 
Update

Wow!!! Thanks to the brain trust for your input. I had a well thought of A&P come by yesterday. His rule outs included timing, intake leaks, and too little area for air flow to exit the engine compartment. Like everyone, he is extemely busy and will help me with assessing intake leaks and timing when he can fit me in. He too has seen new overhauled carbs not meter fuel correctly and has that on the list but believes the others on the list are more likely. Stay tuned for further details of timing and induction lead assessment....

I will try to answer some of the questions that have been posed...

Check engine baffles for leakage and or good seal. CHT on slow taxi , TO and Climb are effected tremendously by leakage and by pass. Be sure all baffles are turned to correct position after cowl installed. Poor Seals at cowl inlet { to lower section} are bypass killers.

Dennis, I checked with a flash light after landing the night before and did not have light transmission from back to front where the baffle contacts the cowl. When I removed the cowl, I found the baffles to be configured the correct way (towards the cylinders) and nice black rub marks on the underside of the top cowl. Looking at the aluminum back stop, it abuts to the back side of cylinders #3 and #4. Air can only move down through the fins between cylinders or between the cylinders and the back side, is this correct? Doesn't seem like there is enough space to have adequate air move through the system to cool??? There's holes cut in the aluminum back stop for hoses to the oil cooler, fuel pump, gascolator, and cabin heater. Hoses appear to be in good shape.

During this climb, what was the airspeed, RPM, and fuel flow? What prop type are you running? It's possible/likely the main jet on the new carb is too small.

Larry

Larry, During the climb, I was at full throttle producting ~ 2,300 rpm at 120 kts IAS. I do not currently have fuel flow or pressure indicators on the engine monitor. The plane has a metal Sensenich prop that was repitched ~ 600 hrs ago shortly after the builder started flying the plane to make it a better cruise setup. I don't have the log book here and will report the actual dimensions later.

Maybe leaks at the intake tube gaskets to the cylinders making everything too lean, regardless of mixture control?

Admittedly I'm watching this thread closely. I've had insanely high CHTs also. But for me that might be a combo of timing maps in the EFII system, using an SJ cowl, and baffles. We'll see this weekend after my 5-month winter overhaul after I switched to a factory cowl and did some timing remapping. ;)

Scott, I will let you know when we finish testing.

I have the same setup, but had to break in engine during summer temps in souther California. After break in CHT?s were still HIGH.

Installed ANTISPLAT cowl flap and it instantly solved all problems of cooling. Just recently installed a second cowl flap ( not required ) but just for additional even cooling.

Its easy to install and worth every penny! Antisplat has great customer service and everything I purchased is of high quality,

Mycool, I found the YouTube video they have on the product...Interesting that he did not comment on how much temperature drop he observed on his own plane with the innovation. Can you share with me how much it has helped your plane?

Sam:

My two cents:
1. Stop flying the airplane.
This will not fix itself. It will get worse, until you resolve underlying issues.
You can choose to fix an unflyable airplane on the ground. In the air you have fewer choices, with worse consequences.

2. Pay for an evaluation by a no-kidding RV expert, to include a thorough inspection, and if safe, a flight to evaluate operations.
Mr. Syracuse comes to my mind.

3. Don't poke holes in the airplane.
Lots of RVs fly, in hot places, without 485F temps on climbout.

R&R doesn't seem to have identified underlying issues. Remove and replace, as you're seeing, is expensive in time, money, and opportunity cost.

The good news:
-you're reading this, I hope, safely on the ground. We're not reading about you.
-this is fixable (with enough information, time, money, and effort.)

Caveats: my perspective is based on reading many Lycoming pubs, operating (1) RV-9A with an 0-320-E2D for a couple of hundred hours, and doing my own maintenance.
I'm no expert!


Good luck, and be safe.

Esco et al, thanks for your very well thought comments. I'm so thankful that my training for PP was with an instructor that was very mindful of safety and my background keeps me constantly assessing risk/reward. The decision to fly to Amarillo was made after evaluating environment, ability to get it worked on, and other obligations. I am grounded now until we move through the stepwise progession of diagnosis...the carburetor was replaced as it was not holding the mixture in flight. The fuel pump was replaced as it is cheap and not knowing for sure how old it was. Now we will diagnose the overheating cylinders....
On your comments about getting knowledgeable people engaged in evaluating the plane....I bought the plane from the builder in Lee's Summit, MO. He was the EAA Chapter 91 President for 25 years and the chapter is very strong with over 100 members and lots of RVers. It was prebuyed by a well respected A&P/AI in the area who maintains many RVs and has built an RV8 that he currently flies. I believe I had a good evaluation done and at that point the engine ran well and did not overheat. I had a wonderful transition trainer who is an RV owner, A&P, and crash investigator for one of the big avionics companies in the area. He took me through 10 hours of training that included a cross country to Amarillo. All was good then. It was once I started flying weekly back and forth that things started going awry. I've had to remind myself that although the plane only had 500 h when I bought it, that was over 15 years...not many hours flown over the last many years because of his health. I believe it is harder on engines and components sitting than working. Now that I'm working it hard, issues are surfacing. I would love to meet Vic Syracuse one day. I love his writing and believe he brings great value to his clients. I believe I received a good prebuy for a whole lot less because he was local and did not have to provide travel expenses.

I keep thinking timing as others have mentioned.

I had an O-320-E2D on my Yankee years ago, and for some reason, the flywheel was not keyed - you could put it on any way you wanted. Sure enough, it got put on one set of bolt holes off - so while it had timing marks, they were completely wrong! To make sure, when you recheck the timing, actually measure the #1 TDC position through the spark plug hole.

Probably not your case...but its one way that you THINK the timing is right, when its not....

Thanks for your comments Paul. The A&P had the same comments about TDC so he will be assessing that when he checks timing.

Yesterday I started R&R the EIS with a 4 cylinder model that will include fuel flow and fuel pressure. As we say in the cattle business...you can't manage what you don't measure. I hope to hear comments on the questions that I posed about the set up for air movement through the engine compartment. I have read many posts where folks have made modifications to the aluminum baffling to improve airflow. That seem reasonable if you are flying with a "hotter" engine but with this one I'm skeptical. Let me know your thoughts.

Thanks everyone for your time and willingness to share your insights.
 
Two thoughts...

Are you throttling back after takeoff, to reduce power requirement and hopefully temperatures? If so, you're putting less cooling fuel into the system at a high-load time. At full throttle there is an enrichment circuit that opens and puts more fuel into the engine for full-throttle operation. I found leaving full throttle in the climb lowered my CHT's significantly on warm days.

Is this engine a former Cessna 172 engine? If so, it's probably jetted for operation at 172 speeds and airflows through the carb. You can tell if leaning during your runup doesn't give much, if any, RPM rise before it drops again. If this is the case, you may never be getting "full rich".

Snowflake...I'm leaving the throttle full and mixture rich. The carburetor is new rebuilt MS MA-4SPA which was the type on it before. I spoke to MS before I replaced the carb and this was their recommendation. But it is possible that the rebuild is not up to specifications. Trust but verify!

The log books were lost in hurricane Andrew back in the 90s so not sure what the engine was in. The current log book states by the man who inpected the engine at the builders purchase that Lycoming estimated it had 2,000 h on it at the time of rebuild.

Great questions and many thanks!
 
Your on the right track.before jumping on the it's to lean drill the jet bandwagon. Get good data. Knowing fuel flow at takeoff will be a good first step. If the flow is in spec then dumping more fuel in to cool it is not the right way to go. Sounds like your getting the timing where it needs to be, a couple of degrees makes a big difference. Also make sure your Cht probes are accurate. A boiling water test will give you a good idea if they are accurate.
It's sometimes a tough road but its worth it in the end. I was battling it in my rv-4 for months but got it so it running about 380 in the climb, and I did not have to drill the jet. Mine was mostly timing and and baffle issues.

Bob burns
Rv-4 n82rb
 
Sam, yes that's correct on the rear 3 and 4 ,you only want air going down THRU the cylinder fins not thru space at the end of the fin. May have miss comment but double check the seal just behind the inlet fwd of1 and 2 such that nothing is getting to lower cowl from upper, theres also two fiberglass ramps bonded to inside of upper cowl that have been left un plugged by builders allowing inlet to bypass air to lowervia tunnel under the ramp. My exp is from a 0320 D2J RV9
 
Unfortunately, my write up on a similar problem I had in 2006 on my 9A is not in the VAF archive. I can only go back 500 postings and I have made over 2000.

Summary:
Cylinder flashing removal (the channel between the plugs)... 20 to 30F reduction in CHTs.

Rejetting the carburator... 25 to 30F reduction at takeoff/climb-out. Without exception, every carburated RV that I know about with a new engine needed this modification. You have a new carb, so this is likely an issue.

BTW, the IO540 on my Rocket needed the flashings removed as well, with similar results.

V
 
Pmag timing set at 25degrees not at tdc?

While timing will increase CHTs some, it will not to the level seen here. I don't believe that you can advance timing enough to induce 485* CHTs on initial climbout, assuming an other wise well configured and baffled RV without seeing detonation or a performance fall off. Seeing CHTs rise 20-40* in cruise power levels would be typical. However, if you keep advancing timing beyond optimal, you will also see your performance drop off.

Having said all of this, I would also think that 485 immediately after take off would be a solid clue to detonation, which wouldn't be overly surprising with too small of a main jet. Very rapid rises in CHTs are often tell tale signs of detonation.

I run 35* timing below 1000 RPM to help with my rough running issues when heat soaked. I can assure you that I have never seen 425* CHT while idling. THe OP is seeing 425* before even advancing the throttle. This makes me question the instrumentation.

Larry
 
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I had a similar problem, tracked it down to inter cylinder baffling.

Rob

My $0.25 bet as above
Also the cowl nose inlet ramps and seals / spinner cowl nose and the combustion air intake sealing can all leak and create vastly reduced airflow through the cylinders even if the inter baffling(under the cylinders) is present and OK.
perhaps $0.15 on timing

Buy Dan Horton a return plane ticket and get Dr. Cooling on site.
 
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Reply

Prior to installing 1 cowl flap (keep in mind it was the first 20 or so hours SMOH) my CHT?s (ALL) would drive up to 440f and i would pretty much after takeoff have to pull back power and climb.

Since installing 1 cowl flap i can pretty much climb all day in 1500? and temps stay around 400f.

I just installed the second cowl flap, and have not yet flown the aircraft. Temps are starting to increase in my area (So Cal) so ill wait until i get a day above 80f ambient to run another test.

BTW I also have a dual pmag setup, ( im sure ill be corrected if not 100% correct) but my understanding is that the pmag setup advances timing with rpm well above 25 degrees.
 
Questions

I have been reading your posts and I have a couple of questions.

In your initial post you wrote

"Had a prebuy conducted and no issues were noted at purchase.

Almost immediately fuel burn went to 11 to 12 g/h and the engine would not run smoothly. Two mechanics later there were multiple fuel leaks found. Replaced the Van's fuel selector valve with Andair. Fixing the leaks brought the fuel use back to 7,5 to 8 g/h but the engine was not very smooth. Found the intake connector hose clamps were loose and tightened them up. Through trial and error determined that when the electric fuel pump was turned on, the engine would turn off! Only use electric fuel pump when priming. The primer was checked and not leaking fuel to the cylinders when not activated.

But in a later post you wrote

"I bought the plane from the builder in Lee's Summit, MO. He was the EAA Chapter 91 President for 25 years and the chapter is very strong with over 100 members and lots of RVers. It was prebuyed by a well respected A&P/AI in the area who maintains many RVs and has built an RV8 that he currently flies. I believe I had a good evaluation done and at that point the engine ran well and did not overheat. I had a wonderful transition trainer who is an RV owner, A&P, and crash investigator for one of the big avionics companies in the area. He took me through 10 hours of training that included a cross country to Amarillo. All was good then. It was once I started flying weekly back and forth that things started going awry. "

Was there any maintenance done between "all was good" and "flying weekly"?

I run my fuel pump for takeoffs, landings and fuel tank changes and the engine doesn't quit (O-360.) What kind of primer system to you have, manual pump or electric valve?
 
Good Morning Update

All, it was a good weekend of diagnostics and working on the installation of the new EIS 4000. We conducted the timing test. Found TDC marked correctly on the flywheel and timing set 25 degrees on both mags. Then did the induction pressure testing and found 3 of the 4 induction tube hoses leaking due to clamps not being tight!!! Wow, when you hear hoof beats, don't look for zebras! As I stated in the first post, that condition was found last fall. Then the clamps could be turned with my fingers. This time, I could not turn them with fingers but had considerable air leakage when tested. The A&P suggested I purchase clamps used for turbo installations as he believes they serve a better purpose. Ram has them for ~ $10 a piece. Anyone have experience doing this modification?

I hope to complete the installation of the EIS today....I'm way too optimistic on how long these things should take, thought I should be done yesterday but working on my back under the panel and entertaining vistors is not efficient to completion! I'll report back once the engine testing is complete.

Scott, you asked about timing of events. The plane ran well after purchase to the the condition inspection (~2 weeks) then for a couple of weeks after the condition inspection (2 or 3 cross countries TX to KS). The transition training occurred between purchase and inspection then another 6 hours after condition inspection. I'm anxious to test the fuel flow with our without the auxillary electric fuel pump on. Should I see more fuel flow with the pump on or does the engine mounted pump theoretically push enough fuel to the carb? The fuel smell that I have been smelling must be the residual from prior leaks in the insulations and carpet on the floor as all connections were tight when inspected this time.

One final nuget. The A&P loanded me his copy of the book that I found available for free as a download here: http://www.alfako.be/SAFETY DOCS/lycoming---flyer_key_reprints.pdf For a newbie at flying and working on the aircraft, I found lots of good information about running and maintaining my Lycoming. For those like me, you may find this a good resource.

Thanks again to everyone who has contributed to the dialogue. Your input has been so valuable. Stay tuned for the engine run results!!!!
 
Good luck resolving your issue(s)!

Hose clamps can be safety wired, as seen in this picture of one on a heat shield.


(Click to enlarge)
 
Good luck resolving your issue(s)!

Hose clamps can be safety wired, as seen in this picture of one on a heat shield.


(Click to enlarge)

Stuff like this is normally checked every condition inspection. Rubber conforms so it's normal for them to relax over time.
 
Update2

It took quite some time to figure out why my fuel flow on the new GRT EIS 4000 was not working...the unit was not programmed for fuel flow before it was shipped. Entered codes and all is working great....wasted a day! Since tightening the induction tube clamps, the cylinder head temps are rising to 415 on the back cylinders and 385 on the front, much better than before. Fuel flow is showing 12.2 g/h in climb at 2,350 rpm, 100 kts IAS (fixed pitch sensenich prop). In cruise at 11,500 ft, 2,450 rpm, leaned to 6.7 g/h, EGT 1425 cylinder 3 down to 1150 in cyl 1. CHT hottest in cylinder 3 at 377, down to 311 in cylinder 1. This seems like a large spread that could be improved. What is the chance this is the oil sump riser issue addressed in Lycoming SB 258 that has been described in other threads? Do you have to pull the carb to determine or can you take off the air filter and observe up through the throttle body? Your knowledge is much appreciated!
 
EGT 1425 cylinder 3 down to 1150 in cyl 1. CHT hottest in cylinder 3 at 377, down to 311 in cylinder 1.

Assuming the EGT probes are installed at a constant length from the cyl head, that spread indicates a problem, assuming no problems with the probes themselves, which seems unlikely if new. First guess would be a clogged injector on #1. That could create the level of leanness that would result in low EGT/CHT's as you are seeing here. What were 2&4 doing? Were they close to #3? In my opinion, an intake leak would not result in this level of power reduction at cruise settings, especially when running at or near WOT.

EDIT: Sorry, just realized this was a carb'ed engine. An intake leak is more likely on a carb'ed engine, but would not rule out other issues going on in that cylinder, such as an intake valve not closing. I suggest some testing at increasingly lower MAP levels. The problem should get worse with lower MAP levels if it is an intake leak. At those levels, it would not be a small leak. A wobble test is in order on #1.

I would first test at ROP before anything else. The carb'ed engines often don't take leaning beyond peak too well and it's possible that yours is worse than most. If everything evens out when ROP, that is your issue. It seems from your posts that there are not problems in take off/climb where your are ROP, so I would start here.

Larry
 
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I would first test at ROP before anything else. The carb'ed engines often don't take leaning beyond peak too well and it's possible that yours is worse than most. If everything evens out when ROP, that is your issue. It seems from your posts that there are not problems in take off/climb where your are ROP, so I would start here.

Larry,

Does ROP = rich of peak? If so, peak is around 1475 for the hot cylinder so am ROP by 50F and what my Lycoming manual recommends for cruise. Yes, this engine does not like LOP....one of the symptoms before I changed the carburetor. Just checked for the induction leaks and and tightened the loose hose clamps holding the rubber induction tube connector. We did not find other leaks. What I didn't share is the bias of front cylinders to back. The pairs are similar in temps front to back with front much cooler. Just curious if others thought fuel distribution could explain the bias????

Thanks Larry for your input. I'm headed to Texas in a couple of hours and will continue experiment with settings.
 
I would first test at ROP before anything else. The carb'ed engines often don't take leaning beyond peak too well and it's possible that yours is worse than most. If everything evens out when ROP, that is your issue. It seems from your posts that there are not problems in take off/climb where your are ROP, so I would start here.

Larry,

Does ROP = rich of peak? If so, peak is around 1475 for the hot cylinder so am ROP by 50F and what my Lycoming manual recommends for cruise. Yes, this engine does not like LOP....one of the symptoms before I changed the carburetor. Just checked for the induction leaks and and tightened the loose hose clamps holding the rubber induction tube connector. We did not find other leaks. What I didn't share is the bias of front cylinders to back. The pairs are similar in temps front to back with front much cooler. Just curious if others thought fuel distribution could explain the bias????

Thanks Larry for your input. I'm headed to Texas in a couple of hours and will continue experiment with settings.

yes, rich of peak. Did you observe the EGT rise to that level and insure that it didn't rise to 1475, then fall? Basically, are you sure you are not 50 lean of peak? 6.7 GPH seems low for that RPM ROP on a course pitched sensi, though you didn't mention your airspeed and I don't know your prop and I have a 6, not a 9. That said, I am guessing you may have not yet calibrated your fuel flow setup. With my catto setup, I slow cruise at 2500 RPM and 7.3 GPH LOP. THis produces around 165-170 MPH. What speed are you producing at 6.7?

While cooling air distribution could account for CHT differences, it doesn't account for the 300* spread in EGT. Have you measured the distance from the probe to the exhaust flange? EGT's can't really be compared unless the probes are the same distance. Are you saying that #2 is also in the 1200* range for EGT? Do cyl's 1&2 also have an observable peak at 1475? If not, where do they peak? My experience when I had a carb was for the front and back pairs to show the mixture imbalance, with each cly in the pair relatively close to one another when comparing their EGT peaks.

I have not seen or heard of the carb'ed engines (in good operating condition) having this significant of a mixture imbalance when run ROP. THey tend to do pretty well ROP or even at peak. That said, I suggest that while leaning, you observe the rise/fall of each cyl at every small movement of mixture knob along with the GPH, so taht you can determine peak for each cyl and when they are occuring relative to one another. THis is a bit tougher with the EIS system, without an EFIS, but must be done to determine any issues.

Good luck with the troubleshooting.

Larry
 
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More Drama

Larry, tonight I took off from Topeka full throttle, full rich, and cylinder 3 went to 500 and 4 to 485 in less than 2 min from wheels up. Cylinder 1 was 385 and cylinder 2 375. Once I could pull back the throttle, I got them below 425 back cylinders and > 330 in the front. Once I got to 3,000 ft I gave it full throttle and climbed to 12,500 ft. Once leaned 50 ROP in cruise the cylinder head temps were 1 - 311, 2 - 348, 3 - 377, and 4 - 366. You are correct, the fuel flow is 7.6 g/h not 6.7 (I can be a bit dyslexic when I hurry). I checked the rubber baffles again with the flash light after I landed and they are snug against the cowl above and nice contour from the intake on the cowl to the aluminum baffle with the rubber. I'm pulling the cowl first thing tomorrow, checking the hose clamps again, pulling the carb, and checking the induction size and shape through the sump to see if the Lycoming SB on induction issues applies. I will safety wire the hose clamps as others have suggested.

Thanks again!

Sam
 
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Larry, tonight I took off from Topeka full throttle, full rich, and cylinder 3 went to 500 and 4 to 485 in less than 2 min from wheels up. Cylinder 1 was 385 and cylinder 2 375. Once I could pull back the throttle, I got them below 425 back cylinders and > 330 in the front. Once I got to 3,000 ft I gave it full throttle and climbed to 12,500 ft. Once leaned 50 ROP in cruise the cylinder head temps were 1 - 311, 2 - 348, 3 - 377, and 4 - 366. You are correct, the fuel flow is 7.6 g/h not 6.7 (I can be a bit dyslexic when I hurry). I checked the rubber baffles again with the flash light after I landed and they are snug against the cowl above and nice contour from the intake on the cowl to the aluminum baffle with the rubber. I'm pulling the cowl first thing tomorrow, checking the hose clamps again, pulling the carb, and checking the induction size and shape through the sump to see if the Lycoming SB on induction issues applies. I will safety wire the hose clamps as others have suggested.

Thanks again!

Sam

The cruise CHTs seem inline except #1, which tied with the EGT data from other report still indicates that cylinder is producing less power than the others. #1 is quite a bit lower than #2, which generally seems in line (fronts are often a bit cooler than the rears, depending upon baffling issues and the size of front blocking plates. If you can't find an intake leak, you need to start looking at other issues, such as a sticking intake valve, etc. I don't know anything about that SB, but do know that the std poor lyc distribution issues should not show this large of a span in EGT/CHT from the others.

The take off numbers are ugly. I don't have a lot of experience with poor baffling, but wonder if it can be bad enough to cause 500* CHTs. I simply don't read about numbers that high. I would do some research on re-jetting the carb. Most carb'ed RVs are too lean with stock jets; Mine definately was. 3&4 may be leaning to best power and it's excess heat, along with baffling in need of attention. At 500*, I would almost start worrying about detonation as a reason. Watching the acceleration of the CHT rise relative to 1&2 would help eliminate detonation as an issue. If 3&4 are rising quite a bit faster than 1&2 are rising, it is sign of potential detonation. The hallmark sign of detonation is an uncommonly rapid rise in CHT.

I would try shallowing out your climb to 140 mph at pattern altitude and see what relief you get in CHTs.

Larry
 
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I'm strongly suspicious of a lean mixture at this point. At full throttle, and full rich, how far can you lean the mix before reaching peak EGT? It should be at least a couple hundred degrees by EGT from full rich - I suspect you are seeing less. That will definitely cause high CHT on takeoff power.

Something has changed recently - you don't suddenly lose cooling air - you have a timing shift or a mixture change going on here.
 
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