Tried searching for this but found only a couple small posts. I know most people will say don't waste your time but I don't care good for them. Just wondering if anyone has done some spark plug indexing and whether they've been able to record any hard numbers on the difference its made in their car such as a change in the EGT's A/F ratio anything of the such.

I'm sure this would make a noticable affect if you did the opposite and put the open side of the plug on the exhaust side and tested it and then moved the open end to the intake side and tested.

 

are you thinking in terms of flow, intake port to exhaust port? seems like a pretty tough exercise for nominal gain.
at spark wouldn't you have a lot of swirl and turbulance, not always from the same direction?

 

I think it has more to do with the way the flame front propogates once ignited. Combustion theory is, just that, theory.

 

think of pouring water into a cylinder, as it comes in, following and moving in an orderly fashion untill it hits the bottom of the chamber. now it is bouncing and swirling in no particular direction. as you raise the chamber floor you reduce the extent of travel of the water, but the turbulance is still evident, now introduce the head cavity and flow is further agitated.

 

Right, I'm not arguing that point.

What I'm talking about is the direction the flame travels once the spark ignites the mixture. The electrode can "block" the flame path to a very minor extent. Indexing the plugs theoretically ensures that the flame propogates in the same direction in all cylinders.

 

Which way do you face the open electrode towards the intake or exhaust valve? I thought it was intake but I read in some other post some guy seemed to think exhaust. Does anyone have any hard numbers? I'd have to think that there are some positions that are better for the plug to be in than others.