Stock Plug Gap

[michigancobra]

Well I finally got around to putting my parts
on the car. Started with the plugs, I would suggest that everyone pull there plugs. Everyone
of mine were gapped between .055 and .061, almost
50% larger then Ford spec. Working the on A-pillar
gauges now.

 

[mjchip]

Hi,

The Ford spec is .42-.46 and all of my plugs were gapped at .42-.43 from the factory.

As an experiment, I opened up the gap to .45 on all of the plugs. My car developed a hesitation at around 3200rpm when at full boost. My gut feeling is that I was experiencing spark blow out. So, I pulled the plugs, regapped them at .039 and the hesitation went away. There also used to be a slight hesitation at 5800rpm which is also now gone. Looks like the stock ignition (i.e. plugs and coils) are just about at the limit at 13psi of boost.

Mark

 

[michigancobra]

I gapped all the new ones to .040, I couldnt
believe the stock ones were so far out!

 

[46stang]

mjchip: funny you mention that! I got my car dyno tune yesterday and my dynograph was jumping all over above 5800rpm! my plugs were all ready regapped to 40 so i think i'm going to need some new plugs or less gap? But i think your right on the plug blowout!
Leon

 

[Cobra'03]

I put in the NGK TR6 an hour ago...all the stock plugs were right on the money at .046...the NGK's came pre-gapped at .042 and I left them there. I have a Moroso precision gapper so I know the numbers are right.