Spark plug threads
Spark plug threads
I had a helicoil in one cylinder and it came out. There is not enough thread to hold a new one. Is there a differant way to correct this problem?
Re: Spark plug threads
quick fix ... if it didn't damage the threads ... install a NEW helicoil - reinsert plug 
Alternative 1 - install a 'keensert' - it is a full threaded sleeve that MIGHT be the same size as the helicoil - but they ALWAYS come out with the plug in my experience. Not necessarily a problem, but not what I really expected. Not sure where you can get them at the moment, but Google is your friend...
Alternative 2 - send it to an 'expert' and he'll weld up the hole and rethread it for you. I'm pretty sure that Brian McCarthy can do that for you. (see top of page for BRM Engineering).
Steve
Alternative 1 - install a 'keensert' - it is a full threaded sleeve that MIGHT be the same size as the helicoil - but they ALWAYS come out with the plug in my experience. Not necessarily a problem, but not what I really expected. Not sure where you can get them at the moment, but Google is your friend...
Alternative 2 - send it to an 'expert' and he'll weld up the hole and rethread it for you. I'm pretty sure that Brian McCarthy can do that for you. (see top of page for BRM Engineering).
Steve
The Racer's Wedge and now a Vortech, FV80
Re: Spark plug threads
Bobc:
There are two sizes of inserts that can be used to repair stripped threads in the spark plug hole. The first size can be done with the head installed. In your case, I think you would have to go to the second size and that is best done with the head off or as Stevan said, it could be welded. The insert is easier and cheaper. If done correctly,they do not usually come out.
Need more info, feel free to contact me.
Dietmar
http://www.QuixoteRacing.com
There are two sizes of inserts that can be used to repair stripped threads in the spark plug hole. The first size can be done with the head installed. In your case, I think you would have to go to the second size and that is best done with the head off or as Stevan said, it could be welded. The insert is easier and cheaper. If done correctly,they do not usually come out.
Need more info, feel free to contact me.
Dietmar
http://www.QuixoteRacing.com
Re: Spark plug threads
Deitmar is corrrect in saying that there are size alternatives in the inserts and choices for types of inserts. When cutting spark plug threads in used heads go very slowly and use cutting fluid designed for aluminum. Often, the aluminum around the plug has been heat cycled so many times it gets "punky" and will chip and crumble when being cut, so use lots of lube. Always use locking compound on the insert when installing and lube the spark plug.
Never install a spark plug without some anti sieze or lube on the threads. Engine oil does not qualify since it will cook hard and become a problem. Visit a local airport and find the aircraft parts supplier. They carry a liquid lube made by Champion Spark Plug company that's a dream to work with. Regular anti sieze is sloppy and can short out a spark plug if over used.
As Steven says, if all else fails and the head's worth the effort, we can weld and repair.
Never install a spark plug without some anti sieze or lube on the threads. Engine oil does not qualify since it will cook hard and become a problem. Visit a local airport and find the aircraft parts supplier. They carry a liquid lube made by Champion Spark Plug company that's a dream to work with. Regular anti sieze is sloppy and can short out a spark plug if over used.
As Steven says, if all else fails and the head's worth the effort, we can weld and repair.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.