spark plug indexing?

[ke6960]

any one do this does it help with either mpg or power??

i was reading on a hypermilling board a few weeks ago about it and ive been thinking about trying to do it


here is a site that explains it and the theory behind it...

im only talking about part 5


How To drill and index your spark plugs for better performance/economy. | eHow.com

Now that you have a very efficient set of plugs you need to install them correctly. Most professional mechanics don't bother to do this either, but you will be glad you did. Saving money at the parts store on high end plugs, and saving fuel at the same time is well worth the extra few minutes of effort. With a permanent marker or some kind of scoring tool (the tip of the 1/16" drill bit works well) mark the position where the outer electrode connects to the base of the plug on the side of the plug where you can see the mark from the top when installed in the head of the engine. When you put the plug in you want your mark to face away from the center of the combustion chamber. The rationale for this is that if the back of the electrode is facing into the combustion chamber your spark is directed toward the outer wall of he cylinder, and a lot of the spark is wasted. You want the spark directed into the middle of the combustion chamber where all the air/fuel mix is. Think about trying to start a fire with a match, but you can't get close enough to the fuel to light it. Put the spark closer to the fuel, and you burn it more completely. This is called indexing, and a good parts store will sell indexing washers for doing just this. Don't use a washer on every plug. first try one plug in the first hole and if it lines up fairly well on it's own your done, if it doesn't line up try it in another hole till it fits in line. You usually only have to use 1 or 2 washers on a V-8. Sometimes you will get all 4 to line up without a washer at all on a 4 cylinder. Note that the washers are all different thicknesses, and are marked in degrees of offset. So if you have one hole that is consistently 90 deg. off use a 90 deg. washer to line it up.

[Spraynlog]

I have tried indexing plugs so the gap faces the incoming air/fuel charge. No detectable difference in mileage or power on a turbo mopar. I also had a Jacobs Omni-Pac ignition on it for awhile. I had the plugs gapped at .050 and it ran fine, but no improvement in mileage or power. I took the Omni-Pac off and forgot to regap the plugs....it started missing under boost right away!
I gapped the plugs back to .035, and no more problems.

I think the indexing idea is from the old 'points style' ignition days. They needed all the help they could get! The ignition in the turbo mopars is pretty good as is. The article was correct about 'platinum' style plugs. Do not use them in a turbo car! The copper style is best, and replace them every 15K or so. Use good plug wires too, spiral core or Magnacore. I have heard Aurora wires are good, Turbovanman is a vendor for them.

[John B]

If you center cut the side electrode you will have pretty much the same effect as indexing.

[contraption22]

The only people that I know index plugs anymore are those that have clearance issues with pistons.

[turbovanman²]

I think it also depends on combustion chamber design. I am going to do it on the van as I have the head off, so it will be pretty easy. If you've got 10 mins, why not, doesn't really cost anything,

Oh, YEP, Aurora wires rock,

[csx#516]

I have noticed on a head with many runs on it the fuel looks to be washing more on the left side of valve that is as you look at it view off block maybe running leaner on new setup and moving back side of plug to right this looks like the direction is flowing. Maybe try rotating it about 45* and see if it makes a difference. lets say when head is in stalled take a black marker. Mark on side oppsite side of the open side of plug thread in and line black mark at the 5oclock mark it may need a shim or try may plugs dont over tighten plug to get it on the mark

better spark more air and fuel it go boom if didnt matter why is there aftermarket ing setups ie (MSN) a let gose a long way

[mpgmike]

I've indexed the plugs on quite a few engines and the fact is that the improvement depends on how badly they were indexed before. If the orientation totally sucked, then you index the plugs, you'll feel a difference. If they weren't too bad before, you probably won't notice anything.

I tried the Pulstar plugs on the R/T and noticed QUITE A BIT OF DIFFERENCE!! I now run them on everything, even the '85 pick-up (Dodge, of course).

Mike

[turbovanman²]

I tried the Pulstar plugs on the R/T and noticed QUITE A BIT OF DIFFERENCE!! I now run them on everything, even the '85 pick-up (Dodge, of course).

Mike

Difference how?