Indexing spark plugs?

[Slide Panda]

Watching a little gear head TV this morning and they brought up indexing your spark plugs.  I'd actaully never heard of this practice - anyone out there actually do it?

[EEL]

Never done but it shouldnt be too hard. Where do you point it again? at the exhaust valve?

[Norm]

Back in the 60s and 70s, a bunch of guys did it but I've never seen or heard of it making any difference at all. We used to race AA dragsters and stopped doing it.
I still like side gapping, center gaps, and wide gaps with high voltage coils, but it's been awhile since I've been in the presence of a dyno.

[rule62]

Never done but it shouldnt be too hard. Where do you point it again? at the exhaust valve?

point the plug gap at the intake valve

[scott_araujo]

Sorta did it once.  I marked all the plugs on my inline 4 and then put them back so that none of them were pointing the total wrong way.  Didn't notice a difference but like using synthetic oil, it made me feel I was doing the best I could.

Scott

[woodyracing]

waste of time IMO.  The effect would be equivalent to like a tenth of a degree of ignition timing at the absolute best.  Considering that unless you've had your cams degreed and your belts perfectly tensioned to 110hz, your cam timing is probably off 5 degrees or so and chances are your valves aren't absolutely perfectly adjusted, the effect your going to have is virtually worthless.  I would equate it to buying a set of worn out brake pads to save weight.

[RB]

i have done it on my S2R, never noticed a difference.

[LA]

We used to do it back in the mid 70's when we raced.  Champion rep at the track said it was good for a couple of HP on our old bev. drv. ducs, Norton, BMW's etc.

LA

[scott_araujo]

Hmmmm....

I think it probably makes the most difference in applications like drag racing, where the engine is running WOT and near redline much of the time.  Also, when you're trying to squeeze every last little bit of power out of a highly race tuned engine running at the limits.  For most of us, not so much. 

As Woody already mentioned, most people's cams are several degrees off.  One of mine came loose and I had to degree them so I know first hand this is ture and that it made my engine run much smoother.  Yet people slap on things like PC3s without even checking their cam timing or doing a proper tune up first.

In summary, I think that spark plug indexing is most likely useful for an engine that already has all the basic set up covered and is planned to run at the extreme end of throttle and RPM. 

On the other hand, this is something very easy to do on your own for very little money and certainly doesn't hurt performance even if you haven't tuned your engine in the last 10k miles.

Scott

[DrDesmo]

According to NGK:

In any case, engines with indexed spark plugs will typically make only a few more horsepower, typically less than 1% of total engine output. For a 500hp engine, you'd be lucky to get 5hp. While there are exceptions, the bottom line is that without a dyno, gauging success will be difficult.

(source: http://www.ngksparkplugs.com/techinfo/spark_plugs/installation.asp )

Cheers,
Adam

[Slide Panda]

So on my trusty 900 wouldn't even pick up 1 hp.  Oh well.  Still, it was something I wasn't aware of before - neat little tweak think that can be done quite easily