spark plug indexing

[Dr. David Fleming]

Anyone ever tried indexing sparkplugs on a Mercruiser 502 and found any performance increase? Anyone found any performance in different brands of plugs - say NGK vs. Champion?

[MOP]

Indexing has been around for a long time, some seem to get results other say not worth it. Plugs makes can be like props! Many people including me like NGK's but in my 383 they don't stay as clean as AC MR43T's, but in two of my road toys they did very well. If you have the time try the indexing may work for you same thing with the plugs.

Phil

[DonziJon]

What is plug indexing..? ...

[Dr. David Fleming]

Somewhere in the exploration of what happens in the internal combustion engine someone started playing around with spark plug placement - and found more horsepower - angled spark plugs that don't go directly into the engine etc. - and "indexing" which is the select fitting of sparkplugs to get the gap pointed down, or open to the intake charge - etc. And they found more power - on the dyno.

By adding up little improvements you are in effect "tuning" the engine. Some of these things work and some don't - usually on a site like this someone has tried just about everything. Searching ways to run faster - Its is a fair question.

[mrfixxall]

Somewhere in the exploration of what happens in the internal combustion engine someone started playing around with spark plug placement - and found more horsepower - angled spark plugs that don't go directly into the engine etc. - and "indexing" which is the select fitting of sparkplugs to get the gap pointed down, or open to the intake charge - etc. And they found more power - on the dyno.

By adding up little improvements you are in effect "tuning" the engine. Some of these things work and some don't - usually on a site like this someone has tried just about everything. Searching ways to run faster - Its is a fair question.

not worth doing unless you have higher compression,, like 14 to 1..

want cheep power install a set of 1.8 roller rockers..

[mrfixxall]

What is plug indexing..? ...

in other words its when all the spark plugs are all lined up in the same position with the exhaust valve is the way we use to do it..theirs special copper washers that go on the sealing edge of the spark plugs to get them all in the same position,,its time consuming.

#4
http://www.ngksparkplugs.com/techinf...stallation.asp

[Barry Eller]

in other words its when all the spark plugs are all lined up in the same position with the exhaust valve is the way we use to do it..theirs special copper washers that go on the sealing edge of the spark plugs to get them all in the same position,,its time consuming.

#4
http://www.ngksparkplugs.com/techinf...stallation.asp

I was wondering how you could get a proper torque on the plug and get them aligned too...copper washers are collapsible? I'm just going to get my plugs to proper torque and that's good enough for me. I do put anti seize on the threads.

[gcarter]

I have to agree w/Fix.
It don't mak a lot of difference.
There have been some exceptions though. In some very early engines, when C/R's were in the 4:1, or 5:1, a lot of time was spent on sparkplug locations, also multiple sparkplugs. Some early Sterling marine engines had as many as six plugs per cylinder. Also, some early automotive and truck engines had valve access plugs in their "non-detachable" heads. Sparkplugs were sometimes mounted into these plugs, so that a person could mount the plug over the intake valve or over the exhaust valve. I've spoken to some owners who said there was a difference in performance.