spark plugs

[sprintdaddy]

Hi fellas
just wondering if anyone on here knows anything about sparkplug indexing, this is a process by which you place washers (shims) under your sparkplugs so the earth electrode (the one on the side of the sparkplug) to face in the same direction. The idea is to face the electrode away from the intake valve, so when the charge arrives you get the full spark front exposed to the fuel/air mix, hopefully resulting in a reasonable power increase. Well that`s the theory anyway.

comments, discussion?.

[Jonny Rochester]

How much increase do you consider to be reasonable?

[rthy]

I think they are more relevant to those piss-poor combustion chamber designs that are common to the V8 engines. I can't see it doing anything in the real world for a pent-roof chamber.

Do you agree Jonny?

[Benno]

<div class='quotetop'>QUOTE (Sam_Q @ Apr 29 2008, 01:02 AM) </div>I second that, more of a gain in non-cross flow or wedge type chambers, and even then the gain is only 1-2kw.
the test i saw was on a L16 datto, 1-2 kw across the the graph. but could have been heatsoak, temp change, pressure change, etc...

[sprintdaddy]

<div class='quotetop'>QUOTE (Jonny Rochester @ Apr 29 2008, 12:02 AM) </div>I wasn`t thinking anything spectacular considering it`s such a basic mod, maybe your right maybe it is only relevent to V8s and such, was just curious whether anyone else had heard of this particular mod.

[Trev084]

Have heard of it but never seen it in action, Those that spoke about it swore by the fact that it delivered an increase, Just buy some super 4's so you have an electrode every 90 degrees

[Ksevn-T]

Although quite off topic; When i was doing my apprentaship in aircraft mechanical engineering i found that the washer (usualy made of copper) thats in between the spark plug and the head made a fair difference and it was evident when you put them on a spark plug tester (dumy cylinder head with a viewing glass of the spark) after gapping them and cleaning them (usualy 8-12 plugs at a time). When theres no washer the electrode emits a weeker spark compared to when you actualy have a washer there. When the spark plug has the washer it usualy emits 3-4 strong blue sparks from the electrode. With light aircraft (Yess, there not cars) the gap and the washer can determine the give or take of a few horsepower. Sorry i can't help with what washer you need.