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  #11  
Old 04-06-2021, 07:14 AM
BH1166 BH1166 is offline
 
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Default Question Doug Knight

Are the numbers you post cold or hot test?
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  #12  
Old 04-06-2021, 07:57 AM
dougknight dougknight is offline
 
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numbers posted were hot...this year. some years have been cold with similar down trending values over the years.

thanks for al the suggestions. Bore scope supposed to be in the mail tomorrow!
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  #13  
Old 04-07-2021, 06:25 AM
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wobble test?
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  #14  
Old 04-11-2021, 07:34 PM
dougknight dougknight is offline
 
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a couple photos of the culprit. Leave it alone and run it? Try lapping it in place? Pull the whole jug? Suggestions welcomed.
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  #15  
Old 04-11-2021, 11:21 PM
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Quote:
Originally Posted by dougknight View Post
a couple photos of the culprit. Leave it alone and run it? Try lapping it in place? Pull the whole jug? Suggestions welcomed.
It does not look like it has a good seal or the carbon buildup on the valve and the seal match perfectly. Do your other valves look the same? Recent videos from Mike Busch seem to suggest "do nothing" if the power output is fine, but there seems to be little risk in lapping if you do it right (like most things in life).
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  #16  
Old 04-12-2021, 04:33 AM
PCHunt PCHunt is offline
 
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I would "Stake" the valve, and run it for a while, then do a compression leak-down test. The valve doesn't look all that bad.

I believe that Lycoming has instructions on how to Stake a valve. It's pretty easy.

If I can find the Staking instructions, I will post them here, but I'm betting someone will beat me to it!
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  #17  
Old 04-12-2021, 08:02 AM
lr172 lr172 is offline
 
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Quote:
Originally Posted by dougknight View Post
a couple photos of the culprit. Leave it alone and run it? Try lapping it in place? Pull the whole jug? Suggestions welcomed.
Looks like at least 3-5 thou of deposits on the seat and therefore 3-5 thou of clearance. If the valve was touching the seat in that spot, the deposits wouldn't be there or at least would be shinny, not matte. Seems quite unlikely that lapping will resolve that type of fit up problem, especially given the fact that you will struggle to get good pressure when working from the stem. Lapping is typically done from the valve side, not the stem side, as you must get a good amount of even pressure at the interface point. Moot anyways if the reason for the poor fitting is due to a worn valve guide or bent valve

If you want it fixed, pull the jug and send it to an overhaul shop. I suspect that you can get the valves reground, guides replaced and a fresh hone for $500 or so. You can re-use the piston and new rings should be $50.

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Last edited by lr172 : 04-12-2021 at 08:13 AM.
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  #18  
Old 04-12-2021, 06:00 PM
wnplt wnplt is offline
 
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I would lap it with a hose and clamp on the hose and pull on the hose as you lap. Iíve lapped that way with good results.
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  #19  
Old 04-13-2021, 12:06 AM
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Quote:
I would lap it with a hose and clamp on the hose and pull on the hose as you lap. Iíve lapped that way with good results.
+1, same here
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  #20  
Old 04-13-2021, 09:04 AM
dougknight dougknight is offline
 
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Thanks for all the reply's/reccomendations. As a first course of action I think I will attempt lapping it due to the fact it is the least invasive procedure and easiest on the pocket book. It is something I may be capable of doing myself without hiring it out and I can always proceed to the next course of action if not satisfied with the results of this one.

I have been attempting to educate myself not only on a fix for this but, what it is and what is causing it. After watching Mike Busch's video "why valves stick" I am convienced these are lead deposits created from running 100ll and running too low CHT'S. CHT'S run about 325*F in cruise. I have always leaned as much as I'm comfortable with both on the ground and in the air, but being carbureted and with steam gauges it may not be enough.
So now to figure out how to raise those CHT'S.

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