Good find.

Here is a good write up on how to index spark plugs. http://www.fordmuscle.com/archives/2...gs/index.shtml
Our spark plugs sit much lower than those in the guide; therefore I have extended the line they used for marking up to the very top of the porcelain (white part). You will now be able to see the index mark as you look down your spark plug chamber. The use of spark plug washers are highly recommended to get proper indexing/torque spec.

Post up some results once you guys try this :) It was one of the most annoying things about the car as it would stutter/stumble below 500rpm without the AC being on. I've also noticed, that with the AC on it still stumbles once in a blue moon; with the AC off however it NEVER stumbles anymore.

Good article...one thing I noticed was the fact that you can try several plugs to get one that indexes the best for that particular hole. I like this idea more so than the indexing washers or spacers. The washers are a neat idea as well, but it seems like a lot more trouble getting the right washer by trial and error and also you are pushing the plug out of the combustion chamber with the thicker washer/spacer. I would maybe suggest buying 8 or 10 plugs and trying to get the ones that index or point to the exhaust port the best. You can always take the extra plugs back (unless you write on them...find a different way to mark them). That was a good article and what I read makes sense. Although I haven't noticed whether my xB drops RPM at idle, I may do this for performance and MPG. It can't hurt, anyway. Once again Grimgrak, good article...and thanks for the tip.

Excellet !! Now we all agree this could be a good thing if done properly...........Great article by the way !! i'm checking mine out today.

Accel makes a tool ust for this. Its a small hand held die thats marked off to show just what size washer to use without having to install it on the vehicle. I'll try to find a pic or take one of mine. Been using one for years to help on cars with multiple spark discharge systems.

http://www.cyclepages.com/ProductGro...roupID=4601935
Here you go

I don't quite get the need for a $16 dollar tool for the job! Usually just setting the electrode so that is not pointed towards the intake will give you some benefit.

This is a great thread! Another good "how to" is at http://www.advanceautoparts.com/engl...0001001sp.html

Some times you don't need the washers, and can move the plugs from cylinder to cylinder till you find the right indexing.

Does anyone have a picture of the underside of the head to show where the opening of the electrode should be ideally placed?

Do the washers need to be flat or tapered?

They are flat, but don't use just any steel washer you have laying around. Spend the money and get indexing washers. The copper material crushes to shape and allows for better indexing without exceeding the maximum torque and possibly stripping the threads on the head.

The benefits of Indexing are debatable. The engine design and operating conditions will dictate the end results. However, it can not hurt and almost impossible to do damage if done wrong (as long as you don’t over torque).

The way I do it is to make a mark on my spark plug socket and put the plug it the socket indexed to my mark. I can then see where the index mark is and get it to within about 1/8 of a turn of the perfect spot. As long as the back of the electrode is not toward the “open” part of the combustion chamber, it is of some benefit.

Yeah I wasnt gonna find any old washer. I noticed there are two styles of copper indexing washers, flat and tapered and I wanted to know which I would need.

:relief:

I was hoping someone would mention this.

Overtightening or loosening spark plugs is NEVER an option, no matter what the desired result.

I don't own an xB, but I remember seeing this being a TSB where they adjusted your throttle cable. Maybe someone can find the article...

I'm going to try this over the weekend, and I'll re-post. Mine also idles rather roughly at times....

anyone with a good deal on these plugs? link me baby!

I've just tried driving about 2000miles without using the copper washers to index the spark plugs. After i put in the washers and torqued them down i've been getting really crappy misires at idles. I suspect the washers have lifted the sparkplugs too high in the combustion chamber. The crappy idle problem has NOT been fixed. After switching to iriduim plugs it went away for about a week and has now come back. I've now tried adjusting the throttle cable and even had the car cold idling at 2000rpm and by the end of the day the ecu will bring it back down to 500-750rpm making it stumble and idle like garbage again. Car has less than 5000 miles on it and this problem is really bothering me. Does anyone know where the idle adjustment screw is? Possibly in the online tech manual? What section?

I would not go making anymore changes, I would take it to the dealership.

i may try this

Some of you guys are pretty dense. You don't force the plug to line up or loosen it if it just wont line up. You either try the plug in a different spot to see if it lines up better or you try another plug. You may go through a few plugs trying to match them up to your cylinder head.