spark plug indexing

[black2kSS]

has anyone indexed their plugs upon install? if so, has anyone done back to back dyno runs to prove that it helps? if you don't know what this is, it's when you shim the plug so that the open part of the plug faces in towards the valves and combustion chamber to help with air/fuel mixture ignition. just wondering if this trick has any repeatable results in our engines

[Knight]

I've never heard of it giving enough of a gain to do it.

[Smittro]

I've never heard of it giving enough of a gain to do it.

This...

Not worth the hassle...

[cammed goat]

I think some plugs come with washers installed for indexing. I could be wrong though. But I don't think you gain much if anything more than what the plug is designed with(iridium, copper, platinum, etc.).

[67CamaroRSSS]

It only really works if the engine has been blue printed and the heads have been ported and flowed with the combustion chambers having been CC'd.

You do all that to achieve repeatable results from cylinder to cylinder (and chamber to chamber). Indexed spark plugs repeat this theme by keeping the spark and flame front equal (and in the same place) in all cylinders.

It isn't worth the effort on a stock engine.

[Too Fast]

It only really works if the engine has been blue printed and the heads have been ported and flowed with the combustion chambers having been CC'd.

You do all that to achieve repeatable results from cylinder to cylinder (and chamber to chamber). Indexed sparg plugs repeat this theme by keeping the spark and flame front equal (and in the same place) in all cylinders.

It isn't worth the effort on a stock engine.

^^^this.

It's worth 1-2 HP, but if you are trying for every last HP.........

[black2kSS]

planned on changing the plugs so i figured why not give it a try. i know it is not gonna be noticable on the seat of pants meter but figured if im gonna have them out then why not.

[nickracer]

Not worth the effort. You can get HP gain from preference alignment of the spark plug, but you have to know the prefered flame front propagation (the way the combustion chamber gases burn most completely not necessarily the fastest) to set the index of the spark plug. Is it worth it on a street car - NO. Starting with a fresh engine build and setting up the head for a certain plug, then tapping the hole preferentially, indexing all spark plugs to the same alignment, labeling each and store sorted for the track, and....yeah that's why it cost so much to win races...

[Smittro]

planned on changing the plugs so i figured why not give it a try. i know it is not gonna be noticable on the seat of pants meter but figured if im gonna have them out then why not.

You've never done your f-body plugs before huh?

If you're not swearing by #4 you're doing it wrong..

Happy modding..

[Knight]

You've never done your f-body plugs before huh?

If you're not swearing by #4 you're doing it wrong..

Happy modding..

That's what I was thinking too. It's enough of a pain just to get them in, let alone make sure they're indexed properly.

[black2kSS]

i have never changed the plugs in an f-body but being a mechanic have had many interesting words during other installs. got the burn and cut scars to prove it. plan on doing header install so thought plug change would be good also. however i did put wires on my last one and remember doing the back 2 from under the car.

[Smittro]

i have never changed the plugs in an f-body but being a mechanic have had many interesting words during other installs. got the burn and cut scars to prove it. plan on doing header install so thought plug change would be good also. however i did put wires on my last one and remember doing the back 2 from under the car.

That's just my 3800 experiance

I hear it's worse for you LSx guys..

[SSnow]

Indexing only works with the older style gasket plugs that require a copper washer to seal them. Different thickness washers are used to limit the rotation in the plug thread.
http://www.championsparkplugs.com/re...p?AAIA=1034783
The plugs used in an LSx engine are seated design. The plug seat makes the seal at the head. If you put anything in between to take up you will lose the seal.
In other words don't bother.

[black2kSS]

well that definitly settles that then.

[Marc 85Z28]

Indexing only works with the older style gasket plugs that require a copper washer to seal them. Different thickness washers are used to limit the rotation in the plug thread.
http://www.championsparkplugs.com/re...p?AAIA=1034783
The plugs used in an LSx engine are seated design. The plug seat makes the seal at the head. If you put anything in between to take up you will lose the seal.
In other words don't bother.

You can index them. You just need to keep buying plugs until you find one that seats in the correct position. You may only need 8 if you're really, REALLY lucky and spend the countless hours removing and reinstalling, matching the plugs to each cylinder. Or you may end up buying dozens of them.

[Knight]

You can index them. You just need to keep buying plugs until you find one that seats in the correct position. You may only need 8 if you're really, REALLY lucky and spend the countless hours removing and reinstalling, matching the plugs to each cylinder. Or you may end up buying dozens of them.

Yeah, that sounds worth it.

[Marc 85Z28]

Yeah, that sounds worth it.

Not with the heads on the car. When I did my build I indexed the plugs with the heads on a workbench. I had to buy 12 plugs in total, and it took me maybe an hour. I have no way of really knowing if it helped power output.