Black spot on spark plug

[bluebombersfan]

I noticed one of my new sparkplugs has a black spot on the porcleain right by the sparking point, its a brand new plug and none of my other ones had this, probably not a big deal I'm guessing, or is it? can that mean something,
No damage or nothing just a black dark spot.

 

[Mark_88]

Note the cylinder that the plug was in, swap one of the other new plugs into that cylinder, then drive if for a day and pull the new plug from the cylinder and check it...if you see the same thing on a different plug then you may have a problem...otherwise, it could be a defect in the coating of the original plug...

I've not ever pulled plugs after they've been installed unless there is a problem with firing or performance...then I just usually check the gap to make sure I didn't bang it on the way in or whatever...

Are you noticing a miss or otherwise a performance issue, or did you just happen to pull the plug for other reasons?

 

[bluebombersfan]

I was doing a compression test pretty much 140 all four. It runs alright but mileage is down and power is down a little too
to my understanding 140psi is possibly excellent.

 

[Mark_88]

That is very good compression...mine were like 114 to 130...

 

[bluebombersfan]

In my haynes Manual the cylinder variation compression chart starts from 101psi and for some reason goes all the way up to 250psi.
I would think a brand new engine wouldn't be any higher then 160psi.