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Discussion Starter · #1 ·
Hello all, I recently had a spark plug pop to discover the hole had been helicoiled. My mechanics tried to do a second but it just keeps popping. Opinions needed here: should I a) send head to machine shop for repair/new spark plug hole or b) get a replacement head? Many thanks for your opinions. Cheers, Marko
 

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Discussion Starter · #6 ·
Jim thanks. I found a time-sert kit that’s M16 1.5 thread repair. I’m thinking this would work better as he has tried a M16 helicoil kit and the hole is now wider. What do you think?
 

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Still very difficult to get it square into the head, plus any bit that has to drill such a large hole will grab that soft aluminum and want to go sideways.
It's almost a job where one would have to clamp the head in a proper drill press or milling machine to do it right.
 

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Opinions needed here: should I
a) send head to machine shop for repair/new spark plug hole or
b) get a replacement head?
Many thanks for your opinions.
I vote for "b" (worse experience than yours with a helicoil : a piece of the helicoil broke and found it’s way blocking the exhaust valve with subsequent damage to the engine).
 

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A short pilot drill and/or pilot reamer will do the job. I've custom ground drills to make them pilot drills when a similar job as discussed needs doing. There are specific angles to grind the cutting edges of a drill bit so it won't grab soft aluminum or brass. I have a full set of number drills all ground specifically for use on soft materials. A skilled person can successfully drill a Shadow head, tap it, and fit a Time Sert without removing the head from the engine. It is tricky, but not really difficult if you have the correct tools and skill.
 

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Discussion Starter · #15 ·
A short pilot drill and/or pilot reamer will do the job. ..........
so I have what is probably a silly question: I see an M16 x 1.5 time-sert thread repair kit. It does not mention spark plug repair. Is this the right kit? Perhaps it goes without saying Jim, I’d prefer something that doesn’t involve the removal of the head, done by a person with the skills to do it.
 

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