[JasonGS]

I just put in new plugs, and decided to see where the electrode sat. Well, on the front head, the "gap" of all of the plugs was facing down, toward the piston. On the back head, however, they were all over the place.

So my first question is, will I gain anything by having them all properly indexed?

If so, should the "gap" be facing toward the combustion chamber or piston?

TIA

 

[T-Keith]

I believe conventional wisdom to point them toward the intake valve.

 

[Ron Vogel]

Point them towards the ex. valve...This is done mostly for streamlining the intake mix. Both valves are closed when combustion occours. It can't hurt to do it, but it's more important for N/A apps. Be careful with the indexing rings, they're kind of soft, you may need to tighten it, let it rest and retighten. They also tend to allow the plugs to back out every once in a while. Not only are the threads in the heads not consistant, but either are the plugs. I used to buy 10 plugs to do an 8 cly, and swap them around until I was as close as could be gotten, and only use index rings on the really bad ones. On a high HP car, indexing plugs will give you some extra HP (anywhere from 3-10 depending).