What's A Good Spark-plug-thread-repair Insert?

Hi all.

I have a blown-out spark-plug hole that was repaired with a helicoil. Looks like that repair is failing.

Saw some posts about a Cal-Van repair kit, but they don't make an insert that works with the 4.6L Cobra. Does anyone know of a high-quality oversized insert like Cal-Van's that will work with the Cobra?

Thanks!

Thanks for the reply. I’m about 160,000 miles. What would you suggest for this working-over?

I’d like to do this repair myself, which basically means not dismantling the engine at all. I don’t even know if that’s possible, given how deep the wells are above the plugs. Then there’s the debris falling into the cylinder.

I have only a parking space in my apartment building’s garage to work in, which sucks.

Well, I don't really follow the management's "rules." Fortunately, my spaces are in a corner of the garage, so I only have cars on one side. My girlfriend and I removed the entire front of her Passat to replace the timing belt and water pump there, with no issues raised.

Other than the blown-out plug, my car has really kicked ass for over 20 years. It has never leaked anything, except a tiny bit of coolant when the radiator went bad last year. I've never even had the AC recharged, and it still works fine (though seldom used).

I have a decent collection of tools and always buy them when I need them, but I don't have an air compressor and thus no pneumatics. Were you thinking of any particular tools for this job? I did buy a cheap borescope a few days ago, to have a better look at the situation. It's $40, and creates its own Wi-Fi access point and sends the images to an app on your phone. Shockingly decent. Haven't had time to use it on the car yet, but I had a look in my kitchen disposal.

My main concern here would be maintaining a perfectly perpendicular approach when reaming out the hole, and also the presence of the helicoil in there. Then of course the potential shavings falling into the cylinder.

I have a decent mechanic, but I don't have complete faith in his analysis sometimes. For example, he concluded that the misfiring was due to a bad spark-plug wire, and then contended that the brand-new one I installed was coincidentally also bad and had the wrong resistance. I bought yet another set, and it had identical (and proper) resistance on that wire. I was able to return the second set of wires, but that's not good troubleshooting in my book.

I would think I could find a crack Mustang shop in L.A., but my past efforts to do so came up with some flaky outfits and bad attitudes.

The borescope I bought happens to have a screw-on attachment with a magnet, so I'm wondering if I could use it to find and grab any shavings out of the cylinder.

Fortunately I'm dealing with the #6 cylinder, so it's fairly accessible.

Thanks for the video. That tap-alignment tool obviously has an angled bottom; wouldn't that be specific to the head?