Author Topic: Avoiding burnt valves?  (Read 681 times)

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phreak97

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Avoiding burnt valves?
« on: March 20, 2019, 12:01:21 PM »
I’ve just done some head work on my 1990 air cooled after losing compression on my second motor. I discovered both motors plus my parts motor had heavy pitting on the exhaust valves which caused leaks.

Is this a well known issue on these cars? Is there any preventative?
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phreak97

Xylaquin

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Re: Avoiding burnt valves?
« Reply #1 on: March 20, 2019, 10:11:18 PM »
Could it perhaps need some lead replacement additive?

phreak97

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Re: Avoiding burnt valves?
« Reply #2 on: March 21, 2019, 12:22:10 AM »
Could it perhaps need some lead replacement additive?

Possibly, I thought that affected the seats but I guess both?
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126Simon

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Re: Avoiding burnt valves?
« Reply #3 on: March 31, 2019, 07:40:35 AM »
Running lean resulting in high combustion temps?

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phreak97

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Re: Avoiding burnt valves?
« Reply #4 on: March 31, 2019, 08:03:58 AM »
Running lean resulting in high combustion temps?

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I don’t think so, it’s happened on three different engines (and carbys). one wasnt even from my car.
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DEYAN IYI

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Re: Avoiding burnt valves?
« Reply #5 on: June 10, 2019, 02:57:14 PM »
If the seats need to be changed, you can use metal-ceramic ones. Not sure exactly the name of the material but it is used in LPG conversations for example.

phreak97

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Re: Avoiding burnt valves?
« Reply #6 on: June 10, 2019, 11:27:49 PM »
If the seats need to be changed, you can use metal-ceramic ones. Not sure exactly the name of the material but it is used in LPG conversations for example.

The head is back on now, I built it with second hand valves and lapped them in, I didn’t really have any money to spend on it. We’re running valve saver additive now.

The seats were fine anyway, just the valves were getting eaten away.
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phreak97

 

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