I was wondering if anyone indexs sparkplugs on LS1's? I haven't heard of this on late model stuff before..

 

I believe with today's electronic engine management systems with individual coils per plug that the "practice" of indexing the plugs has pretty much died. As I remember it was one of those "can't hurt to do it" kinda things, but I'm not aware that anyone really showed it made any difference, especially on a "street" engine .... now an NHRA monster motor ... they probably still do it ....

 

I don't bother on street cars

 

Computer controls and individual coils have nothing to do with this conversation. Indexing spark plugs is all about putting the spark in the "perfect" place to promote optimal combustion/power output. You're talking very very small increases in power and indexing is typically not done for street engines. Now, if your last name is "Force" and you're a contender for some kind of racing championship, then you *might* want to consider indexing your plugs.

 

On all my old iron big blocks and what not, I always did it. I have a set of Ls1 heads on my bench with the plugs in them and saw how alot of the plugs were facing backwards. I was just wondering if any of you guys did it. When I put my motor together i'm going to do it. Why not, can't hurt.

 

I would be interested in doing it also. What kit do you purchase to index the plugs?

BC

 

How do the spark get to the fuel/air mixture?

Charlie

 

go here: http://store.summitracing.com/egnsea...alse&N=700+115
are we being funny??

 

Feebly so apparently. Poster indicated the plugs were in backwards which suggests the pointy end is sticking down in the combustion chamber and the electrode is on the outside. Come to think of it, the seal would be so crappy there wouldn't be enough compression anyway if the plugs were in backwards.

Charlie

 

I do,old habits die hard,Even on my lawn tractor.

 

I would assume that some engines would respond to indexing the plugs differently than others... Depends on the shape of the combustion chamber and such as to how effective it is..

Though I can't help but think that if you have all your plugs facing (gap towards) the center of the chamber you would most likely get a more even burn of the fuel from the center out VS from near one wall out

Couldn't hurt if you ask me

 

i did in my 70 firebird with a built 409 pontiac with 11:5/1 compression and it definately made a difference. that was one of the things i had to do to get the car to run the timing with full advance with 91 octane fuel. this was a street car that turned 7200 rpms though.
in my 71 trans-am with a 9:75 compression 462 pontiac, it didn't make any difference. in fact i could run 87 octane and that didn't make a difference either. that car only dyno'd 304 at the tires and i only rev'd it to about 5500 rpms so indexing the plugs wasn't critical.
i did it in the 70 due to it being a hp car vs. a torque car and back then i used to street race quite a bit and needed the high rpm pull since traction was always limited on the street (four speed)and the car really came to life at about 400 feet.
don't know that i would waste my time on my stock vette. with compression, juice or fi i would. not really for more power, but for efficeincy and to help avoid knock retard.

 

WOW, you are a diehard, INDEXING THE PLUGS ON YOUR LAWN TRACTOR ! No wonder you used small print. You don't race it, do you?

I use Mobil 1 in my riding lawn mower and thought that was excessive !

 

How many plugs did you have to go through to find one that lined up properly?

Charlie

 

Moroso makes an indexing tool, and supplies washers to do the trick. Set one up and then mark the rest with a sharpie. If you want that last bit of power!

 

Shows what I know.

Since the plug thread and the threaded hole in the head and the electrode on the plug all used to be random position relative to one another, I used to mark a line on the plug body opposite the open side of the gap and screw the plug in to be sure the gap wound up facing the cylinder not the combustion chamber roof. One that didn't work in this cylinder probably would work in another and so on, but I occasionally had to go through a dozen plugs to get eight.

How does the washer used as a spacer work on a plug that has a tapered seat and uses inteference instead of gasket/washer compression to create the seal? I've found tapered seat plugs pretty much cinch up in a really short arc and then don't move any further without risking damage to something. If you have a link that shows how this bad boy works I'd like to look at it.

Charlie

 

Index using a set of Moroso plug washers. Can usually be found at local race shop or ordered from Moroso. (Note: DO NOT use a lead pencil to mark...use a Sharpie. I check both depth and direction using indexing tool.

Part # 71900 Tapered seat 14mm .010, .021, .032

Part #62160 Indexing Tool (makes it simple).

1. Index the first plug in the engine
2. Remove plug and transfer indexing mark to indexing tool held in vise.
3. Index remaining plugs with appropriate washer to indexing tool.
4. Install all plugs with appropriate washer in engine

This method usually works for most plugs. Robotic engine machining is so close on modern engines I have found that threads are fairly uniform in depth and starting position. The difference is in the orientation of the plug threads to the electrode gap. Occasionally I will have to adjust 1 or 2 plugs in a set with different washers irregardless of the tool indications. Always check final position.

BTW GM has 2 good Anti Sieze compounds:

12371386 - Nickle Ant-Sieze Lube 8 oz. Safe for all metals DO NOT USE ON O2 SENSORS. Good to 2,500 degrees.

12377953 - Dry Film Anti-Sieze Lube 4 oz. Safe for all metals and O2 Sensors. Good to 2,400 degrees. Liquid dries to dry film.

I will look for a link that shows the above. This info comes from DJ Worm a corvette racer. Don

Procedure listed from same.
You need:
1. High Temp dielectric ink marker
2. Moroso Part # 62160 - Indexing Tool
3. Moroso part # 71900 - 14mm Taper Seat Washer KIT
(30 ea. washers, 10 each of .010", .021", .032" thickness)

Procedure:
1. Mark each plug indicating "gap" side
2. Try plugs in #1 cylinder hole until you find one that fits while torqued correctly and lines up with gap toward interior of cylinder and angled toward exhaust valve.
3. Take that "perfect" plug out and install, using correct torque, in the indexing tool. (The indexing tool is held by a shop vise). Transfer the "gap mark" to the Indexing Tool. ( I use an awl to scribe a permanent mark on the Indexing Tool. Thus, this tool now belongs with this set of heads.)
4. Using the "gap mark", index the other 7 plugs in the Indexing Tool, shimming with the tapered seat washers if necessary, until they all line up.
5. All the plugs are now indexed and can be installed (with the appropriate washer, if necessary) in the cylinder head and should point in the correct direction.

NOTE: In earlier heads there was a great variation in individual cylinder threads and each cylinder had to be indexed also. Thus an Indexing tool was needed for each cylinder. However recent tooling advances...namely CNC machining cut all the individual cylinder threads to very close tolerences. So.... most high end plugs, once indexed in the same tool, line up very close. However you may have to adjust 1 or 2 plugs in a set with a thicker or thinner washer when actually installed in the head.