92hatchLX

NGK splitfire plugs are gapped at what for a 5.0 mustang? I remember pre-gapping them prior to installation but I can't remember what exactly they are supposed to gapped at. The reason that I ask is because I pulled #5's plug and it looks way to clean, there's evidence that there is combustion in the cylinder, but not enough reside on them for putting 5,500 miles on them. I checked the gap and it's currently at .055", is this too much?

silver91gt

yes, I believe the stock gap varies from 0.048-0.052
I just changed mine from 0.048 to 0.050 and it dropped my low end power, but gave me more top end.

92hatchLX

Would you suggest me bringing it down to .050?

settled4automatic

i wouldn't use NGK's in my mustang. my .02

92hatchLX

That's not what i'm asking, and anyways, I wouldn't use anything but these NGK splitfire's.

SpooledupRacing

I was intrestd in this to.. I will be installing new plugs on tuesday prolly gonna use NGK (great universal plug or N/A and boosted application..

but I need the best gap for an 87 5.0 HO 5spd

silver91gt

try it at 0.050 and 0.048 and see which one is better, every engine reacts differently, these are just guildelines.