Re: spark plug recommendations !!
The sweet spot varies due to combustion chamber shape, quench area, Intake to Exhaust size ratio, Exhaust valve positioning and flow characteristics. it also determines how much efficiency can be gained.
GRofT is: The gap should be positioned somewhere between the center (horizontal axsis) of the combustion chamber and the exhaust valve center axsis. The objective is to position it in the lowest flow area to get the best ignition and largest flame front.
In the LS6 it can be anywhere between the 1:30 to 3:00 position in the example you provided.
In the LS7 the larger Intake to Exhaust valve size ratio dictates a more critical positioning and a 2:30 position works best tending more toward 3:00.
Last edited by DJWorm; 07-31-2009 at 12:15 PM.