N40GL
04-10-2012, 08:38 AM
I've decided to put this up to the bright minds at MM.net to 'splain it to me.
What everybody seems to recommend for a supercharged MM is a cold plug (NGK 4177 or NGK TR6IX) with a gap of 0.032".
What Ford recommends for the supercharged 2004 Mustang Cobra (4.6L DOHC) is a cold plug (Motorcraft 12405) with a gap of 0.054".
Can someone educate me on the difference in the gap? Should I be gapping my MM at 0.054"?
History:
I did a Cobra engine swap a while ago (like around 2005, when the #8 Connecting Rod let go and beat the block into sand). I used the Cobra longblock from the Ford Motorsports catalog (at the time), which left me with 8.5:1 compression. I made up some of that by raising boost (Vortech) to 14# PSI. Since I'm going to have the heads off to replace the gaskets, I'm going to replace the plugs. COPs were done about 8K miles ago. Thinking about ARP fasteners, but stock hasn't let me down, and I can't think of a good reason to do that. Running Red Line 10w-30 synthetic.
What everybody seems to recommend for a supercharged MM is a cold plug (NGK 4177 or NGK TR6IX) with a gap of 0.032".
What Ford recommends for the supercharged 2004 Mustang Cobra (4.6L DOHC) is a cold plug (Motorcraft 12405) with a gap of 0.054".
Can someone educate me on the difference in the gap? Should I be gapping my MM at 0.054"?
History:
I did a Cobra engine swap a while ago (like around 2005, when the #8 Connecting Rod let go and beat the block into sand). I used the Cobra longblock from the Ford Motorsports catalog (at the time), which left me with 8.5:1 compression. I made up some of that by raising boost (Vortech) to 14# PSI. Since I'm going to have the heads off to replace the gaskets, I'm going to replace the plugs. COPs were done about 8K miles ago. Thinking about ARP fasteners, but stock hasn't let me down, and I can't think of a good reason to do that. Running Red Line 10w-30 synthetic.