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02-10-2016, 12:17 PM
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Join Date: Mar 2006
Location: SoCal
Posts: 626
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Agreed
Quote:
Originally Posted by N427EF
Agree with Eric, those are all intake valves and as far as I can tell
there are no issues of concern.
What you are looking for is non concentric heat damaged discoloration.
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I agree there does not appear to be any hot spots. What I don't understand in the larger spread in the visuals (Cy 2 to Cy 4). Mix seem close at cruise and I replaced the spider last year in the hope of keeping a balanced mixture at taxi power settings.
Intake #2 does appear to show some buildup near the intake valve seat. I'll retest that cylinder in 10 hours to see if the low numbers just go away.

__________________
JD
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RV-7 N314SY (KWHP)
IO-360-B1B
CANbus based trim/flaps and electrical
Last edited by jdeas : 02-10-2016 at 04:23 PM.
Reason: Add intake valve photo
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02-10-2016, 03:55 PM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Quote:
Originally Posted by jdeas
I agree there does not appear to be any hot spots. What I don't understand in the larger spread in the visuals (Cy 2 to Cy 4). Mix seem close at cruise and I replaced the spider last year in the hope of keeping a balanced mixture at taxi power settings.
Intake #2 does appear to show some buildup near the intake valve seat. I'll retest that cylinder in 10 hours to see if the low numbers just go away.
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I bet that your idle and low rpm taxi the engine runs rough and stumbles from time to time. Especially when hot.
If these intake valves don't look like the edges are hot, can someone provide a picture where you think they are?
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
Last edited by BillL : 02-10-2016 at 04:08 PM.
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02-10-2016, 04:54 PM
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Join Date: Jun 2005
Location: San Jose, CA
Posts: 78
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Mike Busch articles explained it pretty well.
http://spirit.eaa.org/apps/magazines.../2010_7_25.pdf
http://spirit.eaa.org/apps/magazines.../2010_8_25.pdf
Quote:
Originally Posted by BillL
I bet that your idle and low rpm taxi the engine runs rough and stumbles from time to time. Especially when hot.
If these intake valves don't look like the edges are hot, can someone provide a picture where you think they are?
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__________________
Brian Dal Porto
RV-7 Tipper
IO-360A3B6D
Whirl Wind 200RV
Dynon Skyview Touch
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02-10-2016, 05:21 PM
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Join Date: Oct 2005
Location: Vancouver, WA USA
Posts: 908
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I think what Bill is alluding to is what I’m seeing also, I don’t want to put words in Bill’s mouth but what I see is that there is heat destress on some of these valves and are definitely not what I see every year when I look at mine.
#2 is clearly running hotter between 1 and 4 o’clock position then the rest of the valve. From your low numbers on #2 and everything I have read about this, I would personally be seeing this as the beginning of the end for this valve.
#1 is clearly hotter between 5 and 9 o’clock then between 12 and 4 o’clock.
#3 looks hotter between 10 and 12 o’clock.
#4 is in general running the hottest but it’s also sealing the best and its heat pattern is even.
So I’m not sure what to say about #3 and #4 but #1 looks like a problem building and #2 has a problem.
This is only my opinion and in that case if this was my engine I would be sending these photos to my trusted engine Guy at Lycoming and see what he thought.
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02-10-2016, 05:55 PM
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Join Date: Aug 2006
Location: santa barbara, CA
Posts: 1,682
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I don't see ANY sign of heat distress, nor would it be expected on an intake valve. There is uneven buildup of lead oxide (?) on some of these valves, but so what. This can also be seen on the INTAKE valve in one of the pictures in the 2nd of the two Mike Busch articles, although the article is focused on EXHAUST valves, and for good reason, as that is where the problems typically occur. There is no resemblance between the appearance of the heat distressed exhaust valves in the Busch articles and the pictures in this thread of the intake valves.
erich
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02-10-2016, 06:16 PM
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Join Date: Oct 2005
Location: Vancouver, WA USA
Posts: 908
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Quote:
Originally Posted by erich weaver
I don't see ANY sign of heat distress, nor would it be expected on an intake valve. There is uneven buildup of lead oxide (?) on some of these valves, but so what. This can also be seen on the INTAKE valve in one of the pictures in the 2nd of the two Mike Busch articles, although the article is focused on EXHAUST valves, and for good reason, as that is where the problems typically occur. There is no resemblance between the appearance of the heat distressed exhaust valves in the Busch articles and the pictures in this thread of the intake valves.
erich
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You are correct, these are intake valves and for that reason you may also be correct that this is not a problem, I agree it?s the exhaust valves that suffer the most problems, however, maybe not a problem but to my eye #2 does resemble the pattern in the article.
It would be nice to have a better look at the exhaust valves for fun.
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02-10-2016, 07:00 PM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Russ, yes I was trying to get a little self education going.
With a larger picture the indicators can be pointed out.
Intake valves can and do burn, and will look just like these, so save these pictures and JD will keep us posted on the progression. I have very rarely seen an intake valve burn on a liquid cooled engine, but it is not unheard of in air cooled engines. Usually it is either a valve lash too small or very poor original seat geometry or a combination. Statistically, it is the exhaust that goes first, thus the popularity of articles.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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02-10-2016, 09:45 PM
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Join Date: Mar 2006
Location: SoCal
Posts: 626
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reposted photos
I reposted the photos, my first post has the exhaust valves. The top post on page two is the intake valves. I think the intake is simply covered with lead deposits etc but the exhaust valves have a white and somewhat burnt even look all the way across.
My biggest concern was the big change in the intake valve deposits cylinder to cylinder
__________________
JD
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RV-7 N314SY (KWHP)
IO-360-B1B
CANbus based trim/flaps and electrical
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02-11-2016, 04:56 AM
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Join Date: Feb 2008
Location: Austin, TX
Posts: 179
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What model borescope are you using? Those pictures are very good quality.
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02-11-2016, 09:46 AM
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Join Date: Jul 2013
Location: US
Posts: 2,251
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Quote:
Originally Posted by chipf
What model borescope are you using? Those pictures are very good quality.
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I can answer that, as it's my borescope...it's the Vividia VA-400 that was discussed here on the forums a short while ago. I'm very happy with it.
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