How to: Index Your Spark Plugs
Why do this? Indexing your spark plugs can improve the burn efficiency, thus giving a little better performance and MPG increases.
How does it work? By positioning the open gap towards the intake valves so that they can ignite the Fuel to Air ratio right as they come in.
Please take a look at these examples. (Courtesy of www.pulstarplug.com)
As you can see the ground electrode is blocking the fuel expansion, you want it to hit the freshly entered fuel, not the exhaust side where some exhaust gases are still left over.
There are a few ways to improve the spark location, Side Gaping or Indexing. Even with side gaping I would still index them for a more efficient burn.
You can read more about it here, in the "Keying your spark plugs" section.Originally Posted by CarBibles.com
- Spark Plug Head for the Ratchet
- Permanent Marker
- 14mm Indexing Washers (I used Moroso 71910 ones that I got of eBay) - This one is not necessarily required.
-There is Two Ways of Doing This-
1. Using what you have (easiest and quickest way) - This method is suggested for our engines.
You can simply find the best index by trying out different plugs in every cylinder and seeing which one would give you the best index.
2. Using special washers designed for indexing - This method didn't work any better then the first one with our engines.
What happens with this method is, you replace the washers that came with the spark plugs with special indexing spark plugs. There are three different thicknesses of the washers, thus they adjust the index as needed by you.
Knowing issue with this method on our engines is, if you have the spark plugs too low, the piston WILL hit it and make a pinging noise! Another issue is if you lift the spark plug too much out of the cylinder, it will not deliver as good of a spark.
In my opinion, save your money and just go with the method number 1.
1. Take your spark plugs out and find the ground electrode and where it connects to the base of the spark plug. What you want to do is take the permanent marker and draw a line that you will be able to see from the top.
NOTE Only use a marker. Do not use a pencil! The graphite in the pencil can conduct electricity!
2.Try fitting the spark plug and try to get the black mark as close to 6 O'clock, if it is way off, try a different plug or a different cylinder.
3. Reset your ECU so that it can start adjusting to the new spark plug setup. Within a week your car should feel much better. You can reset the ECU by keeping the negative terminal unplugged for about 20 minutes.
Method 2 - Picking up right after you have marked the ground electrode on the Spark Plug.
1. Take off the washer from the Spark Plug, you will be using washers on it anyway
2. Take the spark plug to your car and fit it into the spark plug. Tighten the spark plug and see where the mark shows.
3. Put a washer on the spark plug, and try fitting it and tighten it.
4. You will have to keep on doing that until you have reached our goal, making the black mark face the exhaust valves.
NOTE Sometimes you will have to just pick up a different spark plug and work with it. This is usually the case if you require to use more then one washer.
5. Thats it, now you probably will not end up with a perfect index every single time, so if you will have to try a different washer, etc. Well the only problem is, the washers don't really stay on the plugs and will end up in the spark plug hole...
There is a quick and easy way to fish them out though
6. Reset your ECU so that it can start adjusting to the new spark plug setup. Within a week your car should feel much better. You can reset the ECU by keeping the negative terminal unplugged for about 20 minutes.
Onto the Dyno numbers...
Now unfortunately I do not have a graph for the non-gaped plugs that were just indexed, but I received 2whp by just indexing, then 5whp more by side gaping.