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Discussion Starter #1
Has anyone else ever heard of this? It seemed to help my throttle response a little...we'll see if it has an effect on mpg.

I found this from www.carbibles.com:

There's a little known method of squeezing some more efficiency out of your engine, known as spark plug keying. The idea is simple - expose the spark to the incoming fuel-air charge. If the grounding strap on the bottom of the spark plug faces the incoming fuel-air charge, the spark is effectively 'shielded' from the mixture. Now I know a spark is a spark, and any spark in a fuel-air environment is going to make it burn, but if the spark is facing the intake valves, then there's nothing obstructing the mixture from getting at it. In thousandths of a second, this does actually make a difference to your burn efficiency.

The problem is that when you screw a spark plug into your cylinder head, you have no idea which way the electrode gap is pointing. For best efficiency, it needs to be facing the intake valves or ports as I mentioned above. The solution is pretty simple. Before you install the spark plug, use a marker pen to put a mark on the insulator that aligns with the electrode gap at the bottom of the plug. It's important to use a marker pen and not a pencil because pencil lead is graphite, which conducts electricity. You don't want graphite on the outside of your spark plug conductor!

Once the plug is marked, screw it into the cylinder head remembering that you'll need a quarter turn to snug it up. If the mark on the insulator is a quarter turn from facing the intake valves when the spark plug is finger-tight, you'll know once it's snugged down that the gap will be facing the intake valves inside the combustion chamber.
If the mark isn't in the right place, don't go over tightening the spark plug to force it into position! You can get keying kits which are basically replacement crush washers that are slightly thicker or thinner than the standard one. They come in one-third, one-quarter and one-half sizes, meaning that they can affect how far you can screw the spark plug in by the matching amount. So if you finger-tighten the spark plug and the mark on the insulator is facing totally the wrong way, once it's snugged down it will still be a quarter turn away from the intake valves. By changing the crush washer to a quarter-turn crush washer, you'll be able to get an extra quarter turn before the spark plug is tight, which will solve your problem and the electrode gap will now be facing the right way.
 

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also known as "indexing". most people will tell you its BS, but it doesn't sound like a bad idea to me
 

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Not worth the effort for a street machine. This is done in racing sometimes in order to extract that last little tiny bit of power from an engine.
 

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Discussion Starter #4
well, considering that its a FREE way to squeeze a tiny bit of power (I would think more so with forced induction), and the effort required is lining up a dot to the intake valves (took all of 10 minutes) it was worth it for me! Like I said, I noticed blipping the throttle took less effort afterwards...just wanted to share what I found with the community.
 

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would this really matter?? facing the intake valves?? cause think...i know its all in a fraction of a second but by the time the air/gas is in the cylinder its no longer comming in thru the valves, its floating around in the cylinder til it spakrs and boom, the gas mix is surrounding the plug its self...i mean maybe if it wasnt a hemi design then i would think it would work better...casue the valves are around the plug in a hemi....i dunno it makes more sense in my head right now and i cant fig what to type...but
 

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citystreetsbimmer said:
dum shIt let me put a larger washer to move the plug ferther away from piston. spark plugs have diffrent lenghts and sit a certian depth into the cylender on all diffrent engines for diffrent reasons.
duh its also so you can lower your compression :naughty: :naughty:
 

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Actually, it will have little effect on the depth of the spark plug, and none on compression. The different washer thicknesses are only thousands of inches different. The technique does work, my point is that for a street machine it will not have a great effect. It's not free because you have to buy the different thickness washers, and it can be tedious to do.

Keep in mind that the air fuel mixture does not explode, but rather rapidly burns. This expansion of gases is what pushes the piston down. Keying your plugs enhances the ability of the fuel mixture to ignite and burn a little quicker. It certainly will not hurt anything. I just think the time, effort and money is better spent elsewhere.
 
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