ragedracer1977 Posted April 10, 2020 Author Report Posted April 10, 2020 10 hours ago, carusoam said: If you get to fly it again... take it to altitude slowly... seeing if the reduced VSI, increase ASI helps with the cooling... -a- The cylinders get over 400 in the first 2 minutes after application of takeoff power. By the time the gear is up, at 100agl or so, there's nothing I can do to reduce VSI. I have to climb out at 3-400 fpm. Quote
gsxrpilot Posted April 10, 2020 Report Posted April 10, 2020 9 minutes ago, ragedracer1977 said: The cylinders get over 400 in the first 2 minutes after application of takeoff power. By the time the gear is up, at 100agl or so, there's nothing I can do to reduce VSI. I have to climb out at 3-400 fpm. And you're climbing out full rich? Quote
ragedracer1977 Posted April 10, 2020 Author Report Posted April 10, 2020 40 minutes ago, gsxrpilot said: And you're climbing out full rich? Yes Quote
ragedracer1977 Posted April 10, 2020 Author Report Posted April 10, 2020 Applied takeoff power at 10:38. First cylinder (#4) crossed 400 degrees within 10 seconds. Fuel flow peaked at 15.5 at 11:00, another 10 seconds, and then began falling. All but one cylinder over 400df by 11:04. #1 maxed at 364df. #4 peaked at near 470 at about 12:52. Just about 2 minutes after application of takeoff power. Roughly 1000' agl. Groundspeed was 108 knots, about 125 mph. There wasn't much wind, so that would be similar airspeed Quote
Skates97 Posted April 10, 2020 Report Posted April 10, 2020 5 hours ago, M20Doc said: Here is the MSA Carburetor application guide, this plus the Mooney type certificate should help. https://msacarbs.com/technical-data/engine-eligibility/ Clarence Yes, but you don't want the 10-3878, it is the leaner of the two and will only give 14.5-15 gph at WOT and 2,700 rpm on a Mooney, even though it is rated higher by MSA. There was a bulletin by MSA addressing the problem in Mooneys. The 10-4164-1 will give 16-16.5gph at WOT and 2,700 rpm which has a significant impact on improving CHT's. Will get my whole experience written up this weekend in a thread. (Last night didn't materialize) A11-62.pdf Quote
David Lloyd Posted April 10, 2020 Report Posted April 10, 2020 Think you can still buy this kit for $12.80? Quote
carusoam Posted April 10, 2020 Report Posted April 10, 2020 If only you have a handful of 1962 dollars... Summaryism..... 1) The natural state of the M20C carburetor is a bit lean on delivering fuel at WOT... 2) The enrichment circuit, a secondary nozzle, that mechanically opens and delivers additional fuel... is the big fix for this... but it is not very economical... fuel wise... 3) Different versions of the carburetor became available over time with mods to have different nozzles, probably larger holes... allowing for less restriction... 4) Carbs have always been crummy about being able to distribute fuel evenly between multiple cylinders... 5) Back in the day... multiple carbs would be used to help with the known challenge... 6) Fuel injection is just a simplified carb for each cylinder... 7) Brice’s challenge has some extra complexity... The situation seems to be changing over time, and getting worse... The instrumentation has changed, and has gotten much better... Our ability to openly discuss actual data has sky-rocketed... 8) Possible Next steps... Explore methods of getting more fuel to the carb... cleaning nozzles, different nozzles, re-setup the mixture calibration, re-setup the secondary nozzle... check the electric fuel pump operation during the climb... those kinds of things... Explore changing fuel distribution techniques... see if the hottest cylinder can be affected by various butterfly valve positions... There are OHs available for carbs... Lots of things can change over time Inside a carb... Clogged fuel injectors get documented around here often... it is quite possible a clogged fuel jet may have a similar issue... 9) Richard’s well documented carb experience can be incredibly helpful... 10) When completed... Brice’s carb will be the most studied carburetor since MS was launched... 11) Don’t be surprised when more fuel with better distribution is the answer... (the lesson from newer IO360) 12) could be as simple as an old seal in/on the carb has been compromised... 13) do your best to find the smoking gun if possible... 14) Who does carb OHs... what does it cost? PP summary of what I read about here... Best regards, -a- Determine what you have... document each step that you take... keep good notes on each of the affects that you get... Quote
MIm20c Posted April 10, 2020 Report Posted April 10, 2020 My advice is to pull the prop back to 2500 until you address the carb et al. No reason to keep sending cylinders over 450. You’ll find the difference in climb performance is not that much unless you fly around at gross all the time. The C is a pretty light plane. 1 Quote
carusoam Posted April 10, 2020 Report Posted April 10, 2020 MIm’s suggestion... Is similar to experience of the 310hp vs 280 LB... reducing power output by reducing 200rpm... is approximately a 10% change in power The cooling doesn’t change any... a function of surface area, and wind speed The energy being put into the system is 10% less maintaining CHTs in an LB with 10% more power adds about 2gph in the STC... People have doubled that ‘recommendation’ to over 29gph for best CHT control while making gobs of power... This is done with really tight GAMI spreads as well... Similar challenge...Worth documenting the experience you get with your own engine... Things to keep in mind... at full power... reducing rpm can lead to a more over square condition... (somewhat an OWT) If the engine is already challenged with pre-ignition, this could exacerbate a hidden problem... PP thoughts only, not a mechanic... Best regards, -a- 1 Quote
takair Posted April 10, 2020 Report Posted April 10, 2020 I know you did the intake leak test, but is it possible it changes? Which configuration intake tubes do you have? While the common place to look for a leak is at the cylinder gasket, if you have the o’ring-into-the-sump style, it may leak in an unpredictable way, especially if the sump is worn. Can’t recall what the C has. Do you have pictures of the arrangement? What happens is it seals when cool and as things expand it moves to a worn spot and leaks. I’ve seen it where even a new o’ring doesn’t completely seal. It has been years, so the details of what we did escape me now....wasn’t my plane...probably not even a Mooney. Quote
ragedracer1977 Posted April 10, 2020 Author Report Posted April 10, 2020 1 hour ago, MIm20c said: My advice is to pull the prop back to 2500 until you address the carb et al. No reason to keep sending cylinders over 450. You’ll find the difference in climb performance is not that much unless you fly around at gross all the time. The C is a pretty light plane. I have been. It keeps it from melting the cylinder, but the heat is still not acceptable. 1 Quote
MikeOH Posted April 10, 2020 Report Posted April 10, 2020 29 minutes ago, takair said: I know you did the intake leak test, but is it possible it changes? Which configuration intake tubes do you have? While the common place to look for a leak is at the cylinder gasket, if you have the o’ring-into-the-sump style, it may leak in an unpredictable way, especially if the sump is worn. Can’t recall what the C has. Do you have pictures of the arrangement? What happens is it seals when cool and as things expand it moves to a worn spot and leaks. I’ve seen it where even a new o’ring doesn’t completely seal. It has been years, so the details of what we did escape me now....wasn’t my plane...probably not even a Mooney. WOW! How in the world did you troubleshoot that??? Hats off to you! Quote
carusoam Posted April 10, 2020 Report Posted April 10, 2020 Rob comes with extra skills... Pilot, mechanic, engineer kind of skills... Best regards, -a- Quote
takair Posted April 10, 2020 Report Posted April 10, 2020 Just now, MikeOH said: WOW! How in the world did you troubleshoot that??? Hats off to you! This was years ago.....details escape me....probably more luck than troubleshooting..lol. If you remove the bolts at the cylinder and break the sticky gasket....you can then tell how how well the o’ring seats. It should be tight. Slide the tube in and out slightly, the condition I am describing will have a very loose spot. In a really bad situation I think they have to build it back up and machine it. When you pull the tube out, there is a worn recess. Perhaps one of the engine guys can provide more info. Not even sure how common this is. Quote
ragedracer1977 Posted April 10, 2020 Author Report Posted April 10, 2020 7 minutes ago, takair said: This was years ago.....details escape me....probably more luck than troubleshooting..lol. If you remove the bolts at the cylinder and break the sticky gasket....you can then tell how how well the o’ring seats. It should be tight. Slide the tube in and out slightly, the condition I am describing will have a very loose spot. In a really bad situation I think they have to build it back up and machine it. When you pull the tube out, there is a worn recess. Perhaps one of the engine guys can provide more info. Not even sure how common this is. Mine have rubber connector sleeves, sorry I don't know the correct part name. Quote
Guest Posted April 10, 2020 Report Posted April 10, 2020 O-360’s normally use rubber tube couplings on the intake tubes while IO-360’s use O rings on the intake tubes. Clarence Quote
Guest Posted April 10, 2020 Report Posted April 10, 2020 6 hours ago, Skates97 said: Yes, but you don't want the 10-3878, it is the leaner of the two and will only give 14.5-15 gph at WOT and 2,700 rpm on a Mooney, even though it is rated higher by MSA. There was a bulletin by MSA addressing the problem in Mooneys. The 10-4164-1 will give 16-16.5gph at WOT and 2,700 rpm which has a significant impact on improving CHT's. Will get my whole experience written up this weekend in a thread. (Last night didn't materialize) A11-62.pdf 133.75 kB · 10 downloads The application guide as well as the type certificate show the many models applicable to the 360 series engine, picking the richest model is best. Clarence Quote
carusoam Posted April 10, 2020 Report Posted April 10, 2020 Observations on the last graph... It kind of looks like Air/fuel is robbed from cylinder #1. (cold EGT & CHT...) And given to cylinder #4. (Symmetrically hotter EGT & CHT) note: EGTs are not on this graph... check the other graphs to confirm... If so inclined... open the rubber connector to see if anything is blocking the flow in one area, that would allow flow to occur to the other area... This allows the confirmation of seals on the rubber tubes in case #4 is leaking air... it would be hard to rob from one, and only give A/F to one other... PP thoughts only... Best regards, -a- Quote
ragedracer1977 Posted April 11, 2020 Author Report Posted April 11, 2020 59 minutes ago, carusoam said: Observations on the last graph... It kind of looks like Air/fuel is robbed from cylinder #1. (cold EGT & CHT...) And given to cylinder #4. (Symmetrically hotter EGT & CHT) note: EGTs are not on this graph... check the other graphs to confirm... If so inclined... open the rubber connector to see if anything is blocking the flow in one area, that would allow flow to occur to the other area... This allows the confirmation of seals on the rubber tubes in case #4 is leaking air... it would be hard to rob from one, and only give A/F to one other... PP thoughts only... Best regards, -a- Do you mean the other way? More air/fuel would result in cooler CHT and EGT. Do you mean #1 robbing from #4? Based on the data analysis, savvy doesn't think there is any possibility of anything but a very minor (if any at all) intake leak. They're just not seeing the symptoms. They are agreeing with it most likely being a carburetor issue. I've checked all the rigging, its good. Marvel suggests overhaul every 10 years or so, because o-rings and such tend to dry out and cause the issues I'm seeing. I pulled the logs, it was last touched in 2005, 1300 hours ago. So, regardless of what else I may find, I think it's a good idea to have it overhauled. 4 Quote
carusoam Posted April 11, 2020 Report Posted April 11, 2020 1 hour ago, ragedracer1977 said: Do you mean the other way? More air/fuel would result in cooler CHT and EGT. Do you mean #1 robbing from #4? Based on the data analysis, savvy doesn't think there is any possibility of anything but a very minor (if any at all) intake leak. They're just not seeing the symptoms. They are agreeing with it most likely being a carburetor issue. I've checked all the rigging, its good. Marvel suggests overhaul every 10 years or so, because o-rings and such tend to dry out and cause the issues I'm seeing. I pulled the logs, it was last touched in 2005, 1300 hours ago. So, regardless of what else I may find, I think it's a good idea to have it overhauled. Not a change in the ratio... because the peaks would indicate that already... as what you would be while looking for with a leak... Consider what would happen if perfectly identical air/fuel ratios are being delivered to each cylinder... It looks like one tube is getting more of this air/gasoline mixture than the other three... of the other three... one looks like it is getting less... air/gasoline mixture my language skills are being taxed trying to describe... gasoline, air, and their mixture aka fuel.... If there is an air leak... the A/F ratio would be changing... It would take an unusual blockage inside the carb where these four tubes begin to be able to send more of the air/gasoline stream towards one tube, and less to another... for an easy math type of example... say we have a 400cfm carburetor... where... 400 cubic feet per minute flowed in and out of the carb... ideally, each cylinder would get 100 cfm of air now we let the gasoline flow in... 16gph of gasoline enters, and splits four ways... Ideally, each cylinder is getting 4gph of gasoline... distributing gasoline... it helps to ‘jet’ a spray to increase the liquid’s surface area.... increased surface area... smaller droplets... improves evaporation... add some heat too... swirling the airflow helps distribute the large droplets... the more even the gasoline gets spread around the more even the air/gasoline ratio is across all four cylinders... now look at the EGT for cylinder 1... and cylinder 4... If they were independent engines... it looks like cyl1 is operating at WOT... cyl4 is loafing a bit in comparison... cyl2 &3 are near identical... to each other... early on, but even they are drifting apart from one another over the time of the flight... from the previous JPI graphs... there are rises in the individual EGTs that are worthy of discussion... right as the throttle is being pushed in for T/O and twisted out as you may be doing at 1k’ agl... something is causing the EGTs to behave differently from one another... overall... each cylinder should behave exactly the same... imperfections of carburetors add in a lot of randomness... and variation... But, something is causing some behavior that doesn’t appear to be random variation... pull any graph you like from your JPI... if you want to discuss minute by minute, each change... Some things are obvious... other things like the cyl1’s behavior before and after the inflight mag check.... hottest on one side, coldest on the other...(?) expect that something is driving the changes... Too much for me to have memorized... so I may have dropped some detail... Hopefully the logic is useable.... +1 on contemplating/considering carb OH... as any seal that can allow an air bubble to get in, or fuel to get out... can change its behavior... Give each fuel line a good look see for any blue staining from the fuel selector, to the engine... Still only a PP, not a mechanic... Best regards, -a- Quote
ragedracer1977 Posted April 11, 2020 Author Report Posted April 11, 2020 I appreciate what you're saying, but looking at the overall data, it doesn't agree. #4 tends to be the richest (or 2nd richest) cylinder. Why it's hotter than number 1 even being the richest is probably mostly related to air flow. The problem seems to be that it's the richest of cylinders that are all too lean... Also, I believe I mentioned earlier in the thread that the intake tubes are totally clean. This is a known fact. We also know, from the data, that an intake leak is extremely unlikely. Where does that leave us? Quote
carusoam Posted April 11, 2020 Report Posted April 11, 2020 Hopefully... I eliminated the thoughts of air leaks from my discussion... but... they seem to come back often... Same for cooling... it seems that there isn’t a giant baffle leak causing the challenge... Down to EGTs as the source of the high temp... EGT - cooling = CHT... The four EGT lines should be nearly on top of each other at all times... some variation is expected, more when carbs are used... So... overall the focus seams to be finding what would make the four EGT lines overlay each other... or what is allowing them to spread... Best regards, -a- Quote
ragedracer1977 Posted April 11, 2020 Author Report Posted April 11, 2020 41 minutes ago, carusoam said: Hopefully... I eliminated the thoughts of air leaks from my discussion... but... they seem to come back often... Same for cooling... it seems that there isn’t a giant baffle leak causing the challenge... Down to EGTs as the source of the high temp... EGT - cooling = CHT... The four EGT lines should be nearly on top of each other at all times... some variation is expected, more when carbs are used... So... overall the focus seams to be finding what would make the four EGT lines overlay each other... or what is allowing them to spread... Best regards, -a- EGT is completely a measurement of fuel burned (or not). My feeling is that they’re all over the place because the carburetor isnt delivering fuel correctly so they’re all leaner than they should be. it seems we’ve eliminated everything else. Quote
carusoam Posted April 11, 2020 Report Posted April 11, 2020 Brice, You did it! Used logic to ferret out all the possibilities... and ran me out of likes at the same time! Hopefully, If there is any other underlying possibilities... Somebody will mention that they have seen this before, and what they did about it... Best regards, -a- Quote
Gagarin Posted April 11, 2020 Report Posted April 11, 2020 Over 40 years ago I had a similar experience with one of my cylinders.It turn out that the paint (spray Rust Oleum) that I used to cover the steel fins corrosion was insulating the fins causing reduced heat dissipation and high CHT. Quote
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