I'm not sure who to credit, but I recall seeing a spark plug modification on the 'net and in print which claims to improve combustion, thereby increasing HP/mileage. I recently picked up a set of spark plug wires and decided to replace the Bosch Platinum plugs at the same time I did the wire install. I decided on Autolite 764's.
Basically the mod consists of filing(gasp!) back the ground electrode to midways(or further) of the center electrode. This presumably exposes the spark to the combustion chamber more effectively. The photo below attempts to show the comparison of a typical new plug and after the modification:
http://www.lincolnsclub.org/users/driller/pics/plugmod.jpg
The plug on top has been filed back and rounded off in comparison to a typical plug which overhangs the center electrode completely and is square cut at the end.
A bit of advice here, it is very difficult to file the ground electrode back and round it off without inadvertently hitting the center electrode. My solution was to slide a thin piece if metal between the electrodes to protect the center electrode. I used a paint edger trim tool for this.
After filing I rechecked the gap and set them at 0.048". I applied never-sieze on the plug threads and torqued the plugs to 7 ftlbs. Dielectric grease was used on the plug boots of the new 8.5mm MSD Superconductor spark plug wires(Cobra - # 32219).
http://www.lincolnsclub.org/users/driller/pics/msd8.jpg
Of course the test drive was a lot of fun!
Basically the mod consists of filing(gasp!) back the ground electrode to midways(or further) of the center electrode. This presumably exposes the spark to the combustion chamber more effectively. The photo below attempts to show the comparison of a typical new plug and after the modification:
http://www.lincolnsclub.org/users/driller/pics/plugmod.jpg
The plug on top has been filed back and rounded off in comparison to a typical plug which overhangs the center electrode completely and is square cut at the end.
A bit of advice here, it is very difficult to file the ground electrode back and round it off without inadvertently hitting the center electrode. My solution was to slide a thin piece if metal between the electrodes to protect the center electrode. I used a paint edger trim tool for this.
After filing I rechecked the gap and set them at 0.048". I applied never-sieze on the plug threads and torqued the plugs to 7 ftlbs. Dielectric grease was used on the plug boots of the new 8.5mm MSD Superconductor spark plug wires(Cobra - # 32219).
http://www.lincolnsclub.org/users/driller/pics/msd8.jpg
Of course the test drive was a lot of fun!