That is oil fouled and for the early 8.1L...from the open area underneath the
intake manifold. Subsequent had a sheetmetal pan covering it
All ICE's mist engine oil. Some has a direct route into the intake...others via
the PVC system
Here are the plugs from my 'built' 5.7L 1980 Silverado.
The 'white stuff' is engine oil burned to ash...there are fuel mineral deposits on
all but not this thick.
Turned out to be a cracked heads (both). The porting/polishing/flowed
shop removed a bit too much of the head and intake manifold (Edelberock
High Raise Performer)
These are OEM from my 7.4L and also notice the fuel mineral deposits and the wear
on the ground electrode. Shows the direction of the flame path due to the swirl
(Vortec)
The broken ceramic is most likely from a misfire/pre-ignition/etc. More of a problem
on larger displacement.
I'm not a fan of these expensive, 100K mile plugs and prefer copper cored
traditional plugs that have been 'cut back'. Change them around 30K
or so
Here is what I have in my dad's Caddy STS and really upped its performance
This is what I now have in my 7.4L
Before cutting
just before the cut and has the plug box cardboard shielding the rest
of the plug
Just after the cut
Not many will ever notice but I do.
Think you need to go out and 'blow it out' more often
