Like the tread asks, do you have experience in spark plug indexing? Do any of the tuners reccomend it? Even with stock pistons?
Isn't this forum awesome...Merry Christmas

 

There's no point on these engines.

 

We index the spark plugs on our race engines. These are Big Block Chevy drag race engines with very high compression (16 to 1), domed pistons, methanol fuel, and small chambers.

The idea is it opens up the chamber to the spark for a better flame travel and also prevent the piston dome from contacting the ground electrode and closing the gap.

I use a Moroso spark plug index tool (round aluminum piece with 14mm threads). I have scribed eight equally spaced radial lines on the bottom from the center thread hole to outside and numbered them 1-8.

I screw each spark plug into the tool and write on the plug the “number” from the tool that is next to the ground strap when tight. I also spend some time figuring out which “number” spark plug properly tightens in each cylinder head spark plug hole with the ground strap facing up away from the piston. (This first time you do this with the head it is trial and error, but if you note the “number” it is much easier next time you replace the plugs.)

I carefully gap each spark plug and draw a line with a Sharpie on the porcelain in line with the ground strap. The Sharpie line on the plug, allows you to see which way the ground strap is pointing after you have tightened up the spark plug in the head. The object is to tighten the plug and have the line facing straight up. (A note, I usually buy several boxes of plugs so that I can swap different numbers to get the ground electrode in the proper position. You can also swap thicker/thinner washers for different numbers.)

Now, do we need to do this with an LS7. No, I really don’t think there is anything there. The LS7 engine uses a flat top piston and has a well designed chamber. Several other factors figure in like only 11 to 1 compression, a relatively low RPM red line, and much smaller quantities of fuel in the chamber.
Hope this helps.

 

Nice write-up!

 

Agreed! X2!

 

Vito,

It is people like you Vito, that take the time to share your experience, with a full explaination, that make this forum what it is. Thank you and others, Merry Christmas

 

Ditto

 

Thanks Vito for the information. Very informative.

 

Thanks Vito.A, good info!

 

Great info Thanks

 

I buy about 16-20 tr-6's or plug of choice. I have a mark on my spark plug socket. I match to electrode. I hand tighten each plug in to the hole. It takes 1 to 3 times to find the right plug that faces to 10 oclock.
Which will end up at 11 oclock when tightened with a wrench. Gap when you find a plug you need. Take back the extra's.
I've been indexing for years. Used to use the washers but it's easy to find the right plug.You learn how to sort them out to fit quick with practice. I find the car runs and starts better everytime I do it!

 

I just torque to spec. I am not convinced indexing provides any actual benefit.

 

I would never bother to torque a spark plug. A simple 1/16 turn past
hand tight.
Unless you actually do index your plugs. Then compare how it runs to how it did previously by driving it. This is what people think. Well it helps starting and the car runs better. Each and everytime I index them.

Most people don't believe in better wires and larger plug gaps either.

Some people don't believe in tune-up's either.

 

my impression of "indexing" was to see how each cyclinder was burning too hot too cold and put a hotter or colder plug in that hole. unless you have a cylinder thats burning oil and fouls the plug this is not really nesessary{for the street}, I thought that top fuel motors ran two magnetoes and at least two plugs per cyclinder to keep every thing lit?

 

only for the first 300 feet, then the electrodes all melt and it keeps running by self-ignition...only way to shut it off is to shut off the fuel delivery.

 

i purchased some indexing washers a while back and some new plugs. still trying to figure out the proper orientation that plug is supposed to be installed in.

ive read some that say have the open end pointed toward the "Quench" area.
some say keep the ground strap away from the exhaust valve so it doesn't cause preignition.

now never having the heads off, makes this kind of difficult,, i think ill try with the ground strap facing up, as posted earlier

-Carl

 

Glad to see someone indexing, The idea is to point the electrode at the intake valve. It's hard to get them all perfect. but getting them to 9-11
o'clock direction is what you want. The indexing insures that one or more plugs are not pointing completely away and the spark is blocked by the ground strap and is firing to the edge of the combustion area.
Instead of the center. Makes all cylinder's the same by indexing.
Forget the washers and buy 16-20 plugs . Just don't gap them until your sure your going to use it and you know which hole it's going. Return the rest!

 

[QUOTE=Rock'n Blue 08;1572519576]Glad to see someone indexing, The idea is to point the electrode at the intake valve. It's hard to get them all perfect. but getting them to 9-11
o'clock direction is what you want. The indexing insures that one or more plugs are not pointing completely away and the spark is blocked by the ground strap and is firing to the edge of the combustion area.
Instead of the center. Makes all cylinder's the same by indexing.
Forget the washers and buy 16-20 plugs . Just don't gap them until your sure your going to use it and you know which hole it's going. Return the rest![/QUOTE
Ground strap makes me think of a stap how about ground electrode.
z51vett

 

Using indexing washers effectively reduces spark plug temperature (heat range) it make the plug colder. Index if you wish but don't use the washers.

 

You will find that each spark plug manufacturer's washer is a different thickness. Just save several of the washers from old plugs and you can put together your own spark plug indexing washer kit.