Spark Plug angle

[jimclemjr]

708 manual says to reuse a spark plug it should be an angle of 30 - 45 degrees. I am guessing this is an indexing angle, but I cannot find anything else on this in the manual. Assume it is 30 - 45 deg from centerline of ground strap pointing to intake valves. ???

[LJ3]

I think the SkiDoo snowmobiles index thier plugs. They have shim kits to get them in the right direction. I really can't imagine you get a huge gain from it, but I could be wrong.

[jimclemjr]

Read some tech stuff and watched a video.... and if I understand correctly, on a big motor it can add a couple HP but the main thing indexing accomplishes, is it hides the electrode from the incoming air mix and that keeps from washing the electrode with wet fuel and it helps the heat range of the plug remain more constant. so plugs burn more efficiently, consistently and should last longer.

[jimclemjr]

Got the answer and it is about the degree of tightening after finger tight. So old dogs can learn!