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  #1  
Old 09-02-2019, 08:59 PM
JDA_BTR JDA_BTR is offline
 
Join Date: Dec 2013
Location: Colorado Springs, CO
Posts: 1,379
Default CHT questions again

So 50 hours into flights now. Cyl 3 and 4 seem good at 330 while 1 will run at 355 and 2 at 385. I have cylinder 2 baffling as clean and sealed as I know how to do and had it looked over by an rv10 builder.

I got the advice here to just wait it gets better. But at 50 hours it seems it should be better already.

The area I’m not real sure about is where the uppper canopy seals around the air inlets. Also not sure about the foam at the prop governor but it seems good with a dimple on half the width from the big nut on top of the governor.

I suppose I will leave the top on and remove the bottom cowling and investigate.
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Ser 140142, RV-14A flying - N1463
Ser 83825, RV-8 building - N8638?
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Last edited by JDA_BTR : 09-02-2019 at 10:29 PM.
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  #2  
Old 09-02-2019, 09:34 PM
mturnerb mturnerb is offline
 
Join Date: Apr 2015
Location: Ponte Vedra, FL
Posts: 1,606
Default

Did you keep the dams in front of cylinders 1 and 2? I removed the one on the left and cut the right one down by 50%. Evened out the temps out nicely.

Also be sure to check magneto timing.
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  #3  
Old 09-02-2019, 09:52 PM
JDA_BTR JDA_BTR is offline
 
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Location: Colorado Springs, CO
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Default

The dams don?t seem to matter. I did cut back the max advance of the pmag but the timing is right.
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Ser 83825, RV-8 building - N8638?
USN Ret, Urologist, AME, Repeat Offender
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  #4  
Old 09-03-2019, 12:53 AM
n982sx n982sx is offline
 
Join Date: Apr 2010
Location: Chicago, IL
Posts: 383
Default

Just to be sure, what are the conditions when you hit those temps. I'm assuming your concerned because these are cruise temps. If so, what RPM, fuel flow, MAP, density altitude and OAT values correspond to these numbers?

The 385 is concerning to me if this is what you're getting in normal cruise. I will see 385 only after a long climb at Vy and it will drop sharply when in normal cruise.
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Built and Flying RV-14A N626KM SN 140093 http://n626km.com
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  #5  
Old 09-03-2019, 06:20 AM
JDA_BTR JDA_BTR is offline
 
Join Date: Dec 2013
Location: Colorado Springs, CO
Posts: 1,379
Default

Well it is summer in south Louisiana so it is 95 degrees out. But I can climb to 7500 with a DA of 9000 and set up 22/2400 approx. Oil temp will be 195 and slowly fall. I keep my climb speed around 120 kts and this keeps temps under 400 on cyl 2. I lean for max economy with EGT peak and all EGT peak within 0.2 gph of each other so I think the fuel injection is good. Cruise is 172 kts and cyl 2 drops to about 380 with OAT around 58 degrees F. Cyl 3 and 4 around 325 and cyl 1 around 350.
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Ser 83825, RV-8 building - N8638?
USN Ret, Urologist, AME, Repeat Offender
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  #6  
Old 09-03-2019, 06:27 AM
Nova RV Nova RV is offline
 
Join Date: Aug 2015
Location: Leesburg, VA
Posts: 577
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I would swap sensors with another cylinder and see if the reading is consistent with another sensor before I did anything else. Or you can do the boiling water check and make sure it reads 212 in a pot of boiling water. If those checks give consistent results, I would start looking at other possible reasons. 385 in cruise is high based on other 14s but it's also within Lycoming's "acceptable" range.
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Leesburg, VA

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RV-14A kit # 140243 (flying as of 11/18)

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  #7  
Old 09-03-2019, 07:35 AM
JDA_BTR JDA_BTR is offline
 
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Location: Colorado Springs, CO
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It is not the sensor checked that a while back. I think it is probably how the seals fit at the inlet. I suspect that air is going out the front corners of the inlet and that might change the diff press around cyl 1 and 2 reducing their air flow. 3 and 4 are great with the ram pressure in the back of the baffling driving the air down.
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Ser 140142, RV-14A flying - N1463
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USN Ret, Urologist, AME, Repeat Offender
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  #8  
Old 09-03-2019, 08:50 AM
Bavafa Bavafa is offline
 
Join Date: Oct 2007
Location: Sacramento, CA
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I believe your temps are not bad as they are but I understand your desire to improve and make them better. They seem a bit hotter than most 14s.

One area I would suggest to check is the bottom part of the baffle where it wraps around the cylinder and see if air can scape the baffles on the sides and not reach all the way to the bottom part.
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  #9  
Old 09-03-2019, 08:53 AM
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DanH DanH is offline
 
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Location: 08A
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Take the cowl off and post photos...inside of upper cowl, baffle seals, lower cylinder wraps at cyl 2
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  #10  
Old 09-03-2019, 09:44 AM
JDA_BTR JDA_BTR is offline
 
Join Date: Dec 2013
Location: Colorado Springs, CO
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Ok will do on the pics. I did go after the sides of the lower cylinder baffle and sealed along those edges. Didn?t seem to make a change.

When I put the top cowl on I don?t feel like the inlet is well sealed. I feel like the seals at the forward end of the intake ramp will flex out letting air out up there. Not sure it matters. I?d love some pics of other?s intake areas to see how your seals lie there. It is super tough to make pics of that in closed assembly.
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USN Ret, Urologist, AME, Repeat Offender
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