The one on the left is the trouble one. All the other plugs I've taken out of my LS1 were identical to the one on the right. They are both the same manufacturer and part number, but the left one seems to have some sort of adapter on the threads. How do I get this off? And what the heck even is it and why didn't it happen on all the other ones?

 

Looks like a thread-sert. It also looks like it has seized onto the plug. The best way to handle it would be another one of the same size and red loctiting it into the hole. I would really hate to come across this on my motor, good luck.

 

Agree, looks like someone stripped the head at some point and the insert came out with your plug. You can probably confirm by checking the hole it came out of.

Good luck.

 

So to expand on the explanation above... Basically at some point and time someone stripped the threads out on that spark plug hole. They either took it to a shop or bought the repair kits at a store. Thread-sert is a screw in sleeve to repair damage to the spark plug hole in your head. It then allows you to screw your regular spark plug in to the sleeve so you can continue to limp along...

I had a nightmare of a time with this issue on my ford truck and finally went with new heads and "time-sert" brand inserts as its a common issue on fords and time-serts are the best brand out there as they do not back out if installed properly.

If you look at the the top of that insert is knurled it shouldn't have backed out... You have a few options.

1. Upgrade to better heads 243's

2. Take your car to a qualified shop and have them try and put in a new "quality" insert.

3. Put it back in the way it is and hope it limps you along until you can do option 1 or 2.

Good luck!

If it was me and you have tools, I would recommend option 1. Better head design and only about $300-400 bucks, plus some gaskets.

 

Thanks for the info. I went to Advance and the guy gave me a spark plug tapping kit for $12 with the sleeves. Put the sleeve on the new plug that was exactly the size of the old sleeve. Perfect right? Screw it into the head, goes in kinda funky, take it back out and the sleeve is shredded. Maybe I need to tap the head? Nope. No way in hell am I gonna be able to get the thread tapper in there while the head is in the car. Looks like I'm gonna do some head shopping... If I'm gonna take the heads off might as well upgrade them.

Oh and I can't put the old plug back in. I broke the tip from trying to remove the sleeve on it. Good thing I've also got a Honda.

 

Not a good idea to tap it while on the car anyway, think about the metal you'd be dropping into the cylinder.

If you have the money for new heads I'd definitely go that route and get more power out of it anyway.

 

I couldn't fit the tap in there anyway so I might as well do that

 

Good luck! There are some 799 and 243 heads for sale in the classifieds, should get you back on the road.

 

If it was me, I'd drop the piston to bottom dead center and put plenty of grease on the tap to catch shavings and tap it. Then blow compressed air into the hole to dislodge any that didn't stick to the tap and install the insert.

It's a turd sandwich for sure, I'd take the smallest bite possible. Good luck and let us know how it works out!

 

yeah I done that before. you can reach it with the exhaust manifold off.

i turned the motor until the exhaust valve was open and used compressed air in the spark plug hole to float any debris up to the vacuum cleaner duct taped the the exhaust port.

it was a dirty fix for a dirty ol work truck