Crimmy

Hey guys. Awhile back i stripped out the hole for the spark plug in the engine head. My spark plug is just barely sitting in there right now. Ive come across some rethreading kits but i was wondering if anyone has had any succesful experience with this in the past and knows what size/brands i should be looking for? Any advice would be greatly appreciated. Got my misfiring to stop for the most part. My last spark plug had somehow closed its gap.

InvaderTrax

Did you actually tear the threads out? Or just cross thread a plug? You can usually run a tap in and retread it. If you put grease on the tap it'll catch most of the metal shavings and keep them out of the cylinder

Crimmy

Its probably just a cross thread. I did not realize you need to hand tighten plugs first and was wrenching away at it until i realized it wouldnt tighten. The spark plug was missing its thread about halfway through and i can only assume the engine block is similar as i cannot tighten a brand new plug in.

SHANE 87

I have striped the lower threds on my a spark plug before and all I needed to do was get another plug you might want to try that before you try taping it or rethreadin the plug hole

freegdr

buy one of these and retap the threads in the head you will need air to blow into the hole after you retap it then hand tighten the plug b4 using the rachet and socket on the plug it has both sizes on it old stlye and new style plugs

Lyon

No offense, but if you couldn't get the spark plug in straight and didn't know to start it by hand, you might want to consider having someone who works on cars check it out and let them doing the rethreading. it would suck to ruin an entire head because of a spark plug screw up.

And I have run the kits before with success to answer your original question. They work very well.

jmu427

Check out the Timesert kit. It is a little expensive, but it is a quality product. I bought it used. The good thing is that after I used the kit, I sold it for what I paid for it in the first place.

I blew a plug out of my old 2000 Mustang (the 4.6 2V heads are notorious for this) and repaired with no problems. It made me a little nervous doing the repair with the head still on the car, but if you take your time it works great. It held with no issues. This was also under 8lbs of boost as I was running a Vortech supercharger! Took it to the track on several occasions and it ran great.

BRUNER247

Heli-coil will fix it.

Crimmy

Thanks for the input guys. @shane87 I dont intend to do this on my own. The reason it happned is because i was alone and stranded on a country road with no cell reception. Live and learn sir! Least i had the crap needed to get it running and get home.

Someone else had said try a new plug. I have done so already. Anyways i beleive i had seen the time sert one before. How does this work? It just scrapes away the metal to make new threads? Wont that make it too big for a spark plug to sit properly?

wildbill1

Try chasing the threads as freegdr suggested before you start with a helicoil or a timesert. With a thread replacement kit, you have to remove more material and rethread the hole for a threaded "bushing". If the plug was just cross threaded for the first few threads, you can probably get away with chasing the original threads. If that doesn't work, a helicoil type repair is in order.

Crimmy

What is the name and size of that tool posted by freegdr?

wildbill1

It's called a spark plug thread chaser.

freegdr

http://www.autozone.com/autozone/accessories/Great-Neck-Metric-spark-plug-hole-thread-chaser/_/N-26gb;jsessionid=E697B081E3A7187C58FCBDCC87C567B1.d iyprod1-b2c2?counter=0&filterByKeyWord=spark+plug+thread+c haser&fromString=search&itemIdentifier=70109_0_0_ most auto parts stors have them just make sur it will thread the correct size

5-90

1) If you're going to do a plug hole with the head in situ, strong preference for the bushing-style kits.

2) If you're going to run a tap into the head, fill the flutes with grease. Remove tap every not more than two full turns. Clean out the grease and repack. This keeps chips from getting into the cylinder (where they can really cause trouble!

3) If you use a thread chaser, it's a bit difference. A "fluteless" chaser (or even a "fluteless" tap) will not cut anything, and therefore won't generate chips. You still want to take it easy driving the thing, but it's much easier. If the chaser is fluted, you'll still want to pack the flutes with grease. This will be to catch any crud that gets loosened during the thread-chasing. However, you shouldn't need to pull it out and clean/repack the flutes.

Whatever you do, DO NOT BLOW THE HOLES OUT WITH COMPRESSED AIR! If you do, there are two simple facts:
1) An air blast can loosen chips that otherwise would have been caught by grease, if you'd used it instead. (If you did use grease, you won't have left any chips.)
2) An air blast WILL NOT GET EVERYTHING. Iron chips in an iron bore being worn against with iron rings means you're going to gouge the bores, lose compression, and lose power. You don't need this.

I've done plenty of spark plug retaps in place, so I like to think I've got a pretty good idea what I'm talking about. I've done overhauls on engines that had "just had the retap done" - so I know what happens if you screw it up.

(Nothing wrong with spark plug thread inserts - I also put them in as a matter of course whenever I'm working on an aluminum head, no matter what shape the OEM threads are in. It's a cinch that the aluminum thread is going to get screwed up sooner or later - putting in the steel insert prevents that.)

Apart from the notes on packing flutes with grease and not blowing out the hole with air, follow the instructions on your kit. Most bushing-style kits will come with retaining compound for the bushing - use LocTite #242 or stronger if it does not. (If the bushing doesn't work, you're looking at machine work or outright head replacement anyhow...)

jmu427

You will cut out a larger hole in the head and thread it. Then you basically put in a permanent sleeve that the spark plug will fit in after it is set. It sounds strange that you have this sleeve just chillin' in your head, but it does work. You change plugs and do everything else just like it wasn't there.