kevsgt

Should I replace my SP-514 spark plugs for ones less likely to break? Or leave them as-is if there's no problems? I've put 30k miles on them, and intend to keep the car for a long time, so I don't want to re-encounter the broken spark plug issue at 200k miles.

When the dealer changed my spark plugs at 100k miles, they said 4 of them broke. It wasn't until now that I learned about the TSB and how the tip of the factory plugs tends to seize and break off. According to the invoice from 2015, they used SP-514 for the replacements. I'm uncertain whether these are the same as the originals and thus have the same problem. Since it was two years ago, I also don't know whether or not they applied any sort of anti-seize on the tips before installing.

It sounds like the SP-514s have been superceded by SP-547s, which makes me think the SP-514s still have the seizing problem:
https://lmr.com/item/SP514K/2005-200...14-spark-plugs

Here is a link about the faulty plugs:
http://www.agcoauto.com/content/news/p2_articleid/120

Is there anything to inspect, if I were to remove one? Or would that just increase the chances of it breaking now and I should just wait until I hit 200k miles?

Buck Sergeant

kevsgt, SP 514 is the correct number if it is for your 2006 stang. As far as the breakage goes, all I can suggest is to hold your breath. Just be sure to put a "LITTLE" dab of anti seize on the bottom quarter inch of thread. Just my paranoia, but I change my plugs at least every 50,000 miles. I don't know if this helps the plugs not to brake, but I have had no breaking issues. Just make sure your socket extension is always in perfect alignment with the plug being removed, and go slow and easy.

Derf00

If you are worried about them breaking in the future, and are going to inspect them now...I would just replace them with Champion One-piece plugs (PN 7989). They are one of the only ones that offer one-piece plugs in the OEM heat range. If you go one colder, Brisk offers one.

I'm on my second set of Champions and have had zero issues. Most people like them. Some claim to have issues but from what their descriptions sound like, it's due to user error (not gapping them or dropping them and cracking the porcelain).

Goldenpony

If it were me, I'd change them out for a set of Champion #7989. Use some nickel anti-seize. I'm on my 3rd set of Champions and I like them-and I sleep better.
Put the anti-seize on the smooth barrel, but stop at the bottom about 1/4" from the end. You don't want to get any on the electrodes or it will short the plug out.

kevsgt

So I removed the spark plugs that the dealership put in, which were factory spark plugs that are gapped at .056" (does the gap increase over time/usage?). But the book that came with my car says .040-.050". I'm confused now what to set my new Champion plugs to. They came set at .046". According to AM, early 2006's are .040-.050", while late 2006 are .052-.056". Not sure which mine is, early or late.

Buck Sergeant

Kevsgt, you are correct about the different gaps for the "early and late" issue. I have never heard of this before, and I think even Ford doesn't know what this means. Do they mean different heads were used during this model year ??? If anyone knows the answer to Ford's, well kept, secret please post your answer.

kevsgt

Successfully installed the Champion plugs, with gaps increased to .050" (max of the given range). First cruise went smoothly without problem.

Only one of the eight plugs was tough, to 50 ft-lbs just to unseat but didn't break. Used Deep Creep seafoam on it.

Buck Sergeant

kevsgt, always great to hear of a success. There are a number of blogs addressing this issue. Glad you were able to find the solution.

kevsgt

While this works for me, for now, I don't necessarily have the solution. I'm still unsure whether I'm early or late 2006 and what the difference is. And curious if the gap amount is specific to the car or the brand of spark plug. (Why are the Champions set at .046" without taking car into consideration?)

Derf00

This is just speculation on my part but, The early/vs late model year may just be an overall change that Ford implemented to get a more complete combustion as an interim way to reduce the carbon buildup. That being said, if the plug is the same part number between early/late , then I would use the later gap (.052 to .056) regardless of year. Manufacturers will often update specs and tolerances but rather than reprint all documents related to the subject, they will just say "Okay from here moving forward use this. Everything older use what your used to".

I've always set my champions to 0.054 (middle of the range). I do not use them as they come out of the box and wasn't even aware of the 2006 difference (I have an 08). The early/late 06 now makes sense about the plug gap of the Champs Out of the box. If your car is running fine, you can leave your plugs as they are. Or, if you want, you can pull them and regap them. It's totally up to you.

Oh and the gap is specific to the application so as long as you're in the middle of one of the ranges in this case you're fine. The champions have been out a long time so they probably released their plugs based on the original 0.040 to 0.050 spec.