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Power and Propeller
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Power and Propeller
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Uneven Fuel Distribution to Cylinders
4/26/2017 8:16 PM
Just gonna throw this out there. I had a higher egt on one cylinder and my a/p flow checked the fuel lines. Turns out there was a "dolup "of solder inside one fuel line, either from a repair or from the factory, causing the fuel flow to that cylinder to be half of the rest.
After drilling it out everything returned to normal
8/2/2016 10:59 PM
Update: Post tightening of intake clamps... EGT's have become more balances, all within 75 degrees on last 2.5 hour flight, cruise settled in at 1400 egt, 365 cylinder at 8500 burning 13.8 - way better than before. Still need to complete a suction test and look for any questionable spots. Will do after I swap the #6 intake tube for the extended one to attache the medium size crossover tube. More later...
7/29/2016 10:03 PM
7/29/2016 4:17 PM
Update - de-cowled and found on odd side one very loose clamp and two questionable and minor, only had time for ground run - but all seemed balances and the amount of leaning was less to smooth out - long flight tomorrow so will update
7/29/2016 4:14 PM
7/28/2016 10:55 AM
Up to about 5000'
Skunk- How did you get the picture to automatically open in the thread instead of having to click on the attachment section at the bottom of the post?
7/28/2016 8:28 AM
7/28/2016 8:22 AM
Great info , than you so much for the input...I will post updates after this weekend when i can go through it again...
...one question, your numbers of 23/2400 with approx 14 gph are general what altitude you think?
7/28/2016 12:24 AM
I have had the same exact P-Ponk engine as your's in my 180 since 1996. A new factory 0-time reman P-Ponk'd IO-520D was installed last year and I have seen similar EGT/CHT numbers to your's on the GEM 610 engine monitor with both engines although the engines had different EGT/CHT patterns. Sometimes 1-3-5 was hottest, other times 2-4-6 hottest. Sometimes CHTs are even and sometimes EGTs are even. These engines are notorious for poor fuel/air distribution so your numbers are not all that unusual. My EGT/CHTs wander from even to erratic depending on power/rpm settings, altitude, and mixture. I usually run 23" and 2400rpm at about 13.7-14.3gph up to about 5000'msl.
If you have an air leak in the intake manifold, it will show up worse at idle rpm where the intake pressure is the lowest. At higher rpm, the throttle is open more and intake pressure will be closer to atmospheric pressure with less air flowing thru the leak causing less of a noticeable problem. If there is a leak, it will show up as a rough idle and one or more cylinder EGTs will go to zero but will pick up as throttle is increased.
The easiest way to test for an intake leak is to connect a leaf blower or high output shop vac discharge to the carb heat hose going to the carb. Turn the carb heat "on", go to full throttle, and start the blower which will pressurize the intake system. Don't worry about leakage from the carb heat box itself. Using a spray bottle filled with soap/water solution, spray all of the hose connections on the intake. Any leak will clearly show up with bubbles.
I have the small crossover tube from the original O-470K which Steve Knopp recommends which had to be changed over from the old engine to the reman. Both hoses between the crossover tube to intakes on both sides had small leaks that caused two cylinders to drop offline at idle. Once the clamps were re-positioned and re-tightened, the leaks went away and the engine idled great.
Hope this helps, good luck but I don't think there is much you can do except fix any leaks.
7/27/2016 9:54 PM
i think there must be air leaking into the collector or at the first connection for hose clamps to I take tubes ... Will be tearing into it shortly
7/26/2016 9:41 PM
Environment: o-520 (carbed) with 8.5 pistons, all new cylinders nickle, 8.5 comp pistons, all fuel supply polished, carb is a pponk modified venturi, new mags, wires and plugs, using jpi 930 to monitor, total time is 37 hours smoh,
minor note: the crossover tube is the smallest one, will be changed out to the medium one shortly
Observations: Cylinder 1,3,5, run an egt temp 125-150 above the 2,4,6, - temps on 1,3,5 all run 1400-1430 fairly evenly, temps on 2,4,6, at same time run 1300 fairly consistently - I have graphed all the flights and using EZ Trends it is very apparent and easily noted that most all flights share lot of similar characteristics of temps.
I have seen varying temps before,but never so lop sided from left to right like this.
Note: all cylinder temps are what you expect as 6 is the coolest and 3 the hottest but they are still fairly close overall
Fuel burn scenario - 22/2350 at 7500 with egt on 3 at 1425 and cylinder at 370 burning low 14's gph
Any thoughts as to why such a one sided temp difference?
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