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I could not see any visible damage to the exhuast
valve on my #5 when it ate a screw but when tested by the cylinder shop the
exhuast valve was leaking due to damage from the screw exiting. Even if the
valve was fine the shop ground off all the burrs and high points caused by the
screw to prevent them from becoming a source of heat that causes the mixture to
ignite early. Preignition will quickly ruin your day and the engine.
Maybe I missed it. Did your friend pull #2
cyl and have it checked and cleaned up? I not an A&P, but I would recommend
it. I did the R&R myself for the cost of a few gaskets. The local shop
charges a flat $300 for the job. That, plus the cost of any cylinder work is
cheap insurance, in my humble opinion.
Paul:
As far as I know, they did a compression check on all the cyl's and they were all (including #2) above 76/80. I'm not an expert on this at all, but wouldn't that indicate an intact valve seat(s)?
Thanks for you help in originally bringing this to our attention.
Erik Larson
Legacy
N74FX
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