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Helicoil

Joe Jet

Member
Any thoughts or comments about spark plug helicoil replacement on an 0-320? Lycoming SI 1043A insists that you go .010 oversize.
 
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If the helicoil needs replacing, the likelihood is very high that there is some damage to the threads in the head, meaning a like for like insert replacement could fail. Therefore, the recommendation seems sound to me. The oversize insert will require re-tapping with an oversize tap as well. Even if the current insert hasn't failed, the operation for removing the old one is likely to gall the alum threads, also requiring a re-tap and oversize insert.

This is a recommendation I would follow.

Larry
 
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I just went thru replacing one and have learned a lot as a result.

You are correct about the recommendation by Lycoming in regards to the over size. There is a SI for it and you will need the special tool that hopefully you can rent as they are expensive. Not sure what question you have but feel free to reach out and I will be happy to share all I have learned.
 
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