Indexing Spark Plugs - How Thick of Washers?

[Whorse]

I've read about this before, and marked my plugs today to see if I could get them lined up properly, and sure enough, cylinders 2 and 3 are exactly like everyone has said, which is not lined up without a washer to raise the threads.

What have people used successfully, and is there any worthwhile benefit, aside from consistency between cylinders?

EDIT: Here's a picture. If you look closely, the black lines are at the BOTTOM of the electrode, so I want them to be down, so the plug is facing the rest of the head.

[guyd_15]

When we raced karts we always indexed the plugs. Indexing washers come in several thicknesses. Sparkplugs vary so you have to switch thicknesses. We always used the ground electrode to shield the gap from the fresh intake charge. I wold believe this might be an even greater advantage with forced induction, especially at high boost levels. Using the ground electrode as a shield combined with a smaller plug gap would probably reduce the chances of spark blowout. Most good speed shops will have indexing washers on hand. All speed shops can order them.
Guy

[Dave]

Why would you add washers to the spark plugs? What would you gain?

I'm kind of retarded here on ignition shat still, so forgive me. Isn't indexing when you point the elctrode towards the intake valve?

[guyd_15]

Dave,
By putting indexing washers between the sparkplug and it's seat you can control where the gap on the plug points in the combustion chamber. It's another tuning aid. It's easy to make horsepower gains at first, however, the further you reach it gets increasingly difficult to achieve even small gains. When we raced karts we were limited by class rules, so even small gains couldn't be overlooked.
Guy

[Whorse]

Yes the purpose is to line up the electrode so the spark faces the majority of the combustion chamber. The washers are used as spacers so you can tighten the plug up properly to do this, without leaving it loose or overtorqued.

[mpgmike]

Funny I should jump on here and see this today as I just indexed mine on my '84 Charger. I only got 1 to line up without washers, and even then I was shaving the washers to get them to line up. I ordered an indexing kit from Summit about 7 years ago. It included about 8 each of three different thicknesses. The idea is that one of the three will get you pretty danged close. Don't know which of the 3 I used all up, but I'm working with only 2 sizes lately. Guess it's time to order in another kit.

Incidentally, the engine smoothed out tremendously afterwards. I want to check mileage as I've got it up to 42.9 mpg thus far.

Mike

[Whorse]

Any guesses as to how thick you used?

I guess I could do the math using the thread size and rotational distance.

[ssheen]

thanks for this tip

[guyd_15]

Whorse,
No need to do complicated math!!!! Get a permanent marker, make a mark on the plug porcelin (this helps you know in which direction the ground electrode is located), then just use trial and error to get the gap pointed in the direction you want. I know it may sound complicated, after you do the first one the rest will be easy.
Guy

[Whorse]

Whorse,
No need to do complicated math!!!! Get a permanent marker, make a mark on the plug porcelin (this helps you know in which direction the ground electrode is located), then just use trial and error to get the gap pointed in the direction you want. I know it may sound complicated, after you do the first one the rest will be easy.
Guy

Click on the thumbnail I posted at the top of this thread

[WVRampage]

So you want the ground to face the intake valve?

[BadAssPerformance]

I've indexed plugs before by just installing them with lines then swapping them into different holes until they were all closest to the correct direction. Can buy 8 plugs and pick the best 4 too.

[jckrieger]

I've indexed plugs before by just installing them with lines then swapping them into different holes until they were all closest to the correct direction. Can buy 8 plugs and pick the best 4 too.

I would do as JT said if you want to try indexing your plugs. My buddy with his GN had misfiring problems at the track after a shop indexed his plugs. Solution? He removed the indexing washers and went right into the 11's .

Personally, I think indexing the plugs is way more trouble than it's worth. I mean, if you want an indexed plug use a Bosh platinum 4, lol.

[Whorse]

I don't see how it's much trouble. 10 bucks for some washers and a few minutes of trial and error.

[BadAssPerformance]

The problem that jckrieger mentioned is caused by the washers cuz they make extra places to leak under high cylinder pressure.

[Whorse]

I would think that good indexing washers would hold, but point noted. Thanks!

[t3rse]

or you could just buy these plugs:

http://www.briskusa.com/products.htm#multispark

(very bottom of page)