[83transam350]

Has anybody tried to index the plugs on a SV? I have done this with some success on my race car, but that was a much bigger engine. It only made a few more hp on the dyno, but for a mod that cost around $10, you cant complain.

 

[Spierings]

Has anybody tried to index the plugs on a SV?

?? What do you mean?? Other plugs??

 

[scottyb0119]

he means facing the open end of the plug at the intake side or is it the other way around, anywho I doubt it would matter much since the plug is in the middle of the cylinder

 

[bob griffin]

I've indexed plugs in the past (Big Kawa and Honda 4s) and noticed a slight improvement (emphasis on slight) . Harley tuners years ago did this as well(that's where I learned it ) with improvement noted../I can't find 10 mm spark plug indexing washers or I'd do my SV (08) right now!

 

[andyauger]

It does work some. Without indexing washers it takes a couple of extra plugs to get the right orientation. That can be a problem if you're using platinum tips, for example. Pricey.

 

[locoblanco]

It does work some.

please explain.
i'm trying to figure out why it works and all i can come up with is that it changes the direction the flame front will travel after ignition. if this is true, i can see why it would work on a wedge head design, (automotive engine), but i don't see why it would make a difference in a hemispherical combustion chamber.

 

[andyauger]

The idea is to get the incoming charge spraying into the spark gap instead of "finding its way around the ground electrode". I don't know why it works, but it does a little. The idea is to get the open gap pointed toward the intakes. On V-8 engines you make a mark on the same side of the insulator as the ground electrode. Spin them in finger tight and see where the mark is. Since finger tight + 1/4 turn is a good tightening practice, make sure the mark is 1/4 turn away from the exhaust side of the cylinder. You keep moving the plugs from cylinder to cylinder until you get a good enough alignment, or you get a couple more plugs and try again. As mentioned, you can get indexing washers, but I've never used them.

I suspect that some of the improvement is due to the incoming charge both cleaning and cooling the electrodes.