Twin plug Heads

[Ol' Ron]

I think placing a plug directly over the center of the piston offers very little in the way of performance or economy. With piston to head clearance down to .050" or less, What does it do?? Very littler there to go bang. The original location was picked to clean the plug during the exhaust stroke. Remember you had to clean or replace your plugs every 5-10K miles. Relocating to the transfer area is the most logical place, using an extended reach plug. IMHO