Re: Clean spark plug, oil on threads
I'm reaching out to the team to get some thoughts on my recent findings. I have about 550 miles on my newly rebuilt 396. I was doing some plug readings the other day, just to find that the #2 spark plug has oil on the threaded portion. The plug is burning clean and indicated it was slightly lean, so I corrected that by fattening up the jets by two sizes. Also, the ground strap indicated that the plug was too cold. What would cause the oil on the threads of the plug? I'm running 10w30 royal purple break in oil.
Your intake manifold may have loosened slightly during break-in and might be sucking some oil from the lifter valley and throwing it on the plugs. Also, valve cover gasket might be leaking a little bit. I would tighten both the intake manifold and the valve cover.
Also, are you running a correct PCV valve for your cam ? if not, you may be getting some light crank pressure that is pushing some oil out at WOT, which is hard to figure out at idle.
1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers