Wally39

Anyone know where I can buy index washers for my 06 Mustang spark plugs? Reason I'm asking is because sometimes when I floor my car and kick in the boost I have one cylinder where the piston likes to hit the electrode on my spark plug and short it out.

bigray327

Jegs sells them.

How do you know that's happening? If it was, you'd see it all the time, not just when you're in boost. The max travel of the piston and the location of the spark plug don't change with RPMs.

Wally39

Because when I remove the plug, the one electrode is touching the other one like it was pushed. I just don't know what else could cause that under WOT.

candymanjl

what he said, the piston travel is always the same unless a bearing is going, then you have bigger problems.

it's probably more likely that you have a bad plug and/or the wrong gap and it's not sparking with the increased resistance of the extra cylinder pressure. I know Kenne Bell suggests upgrading the ignition at 15 psi. it's possible an aging ignition could need some help at a lower boost level, just an idea.

candymanjl

an aging plug or too much heat could do that. are you running the stock heat range or one heat range colder?

Wally39

It happens to any spark plug in that cylinder. Maybe the gap isn't correct and once in a while it won't spark like you said. It's gapped at .032 And yes they are one heat range colder

candymanjl

hummm, try going to a .030" gap and if that doesn't work then a .028" gap. sometimes a small change in the gap can make a big difference and it takes a little experimenting. KB suggest a .025" gap at 15psi, not sure what they suggest below that though, they just said to go one range colder.

157dB

Aftermarket pistons?
If your piston is deflecting enough at boost to hit the electrode,
you have way bigger problems...
BTW, The electrode is in the center and the ground
is what you adjust for spark gap...
Too much ground electrode heat and it turns plastic and
bends where ever it wants to....