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Valve Problem

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Marc W

Well-Known Member
Joined
Mar 31, 2017
Messages
1,234
Location
Colorado
My 2180 VW started misfiring shortly after take off. It was right at 32 F. and it was about 80% relative humidity so I naturally suspected carb ice. I put the carb heat on and no help. I have an A/F monitor and it had gone way lean so I richened the mixture and that helped but it still was misfiring badly. I wasn't far from the airport so I just headed back and landed and put it away. I started it up when the temps were warmed up and it still misfired so I don't think it was carb ice.

I did a compression check and #4 was down a little. I next did a leakdown and #4 exhaust valve was leaking. So I pulled the head and took it apart. I only have about 50 hours on a valve job. I don't think the valves look right. I am not sure the valve grinder did a very good job. The intake valves are both hitting on the inside of the seat. The exhaust valves seem to be hitting evenly across the seat but the leaky valve is not seating all the way around.

First picture is cylinder #3 where the valves were sealing. You can see the shiny ring on the inside of the seat on the intake seat.
upload_2020-2-21_17-24-42.png

This is #4 with the leaking exhaust valve. Again, you can see shiny ring on the inner edge of the intake seat and the carbon toward the outside of the seat. You can't see it but the exhaust seat toward the top is all carbon.
upload_2020-2-21_17-29-45.png

I am not an auto machinist so I am not sure about this. It is my understanding that the valve should contact the seat on the outer edge of the seat first. Am I wrong?

Do these seats look like they were ground correctly?
 
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