Follow up 2. Recent 390 Rebuild. Smoking still. Oil on 7-8 cylinder plug threads.Help

[stotzbotz]

Thanks for taking the time again to give me your thoughts on this matter. I am at about 300 miles on my break in of a recent 390 rebuild that was bored .060 over which of course has new pistons and rings. This engine does have a high performance racing cam, solid lifters and some heavy duty springs. Sorry I can't give more detail on these parts. I am currently still getting blue smoke coming out of the drivers side exhaust when idling after warm up and a fair amount of constant smoke coming out of the driver's side exhaust while going down the road. Tonight I pulled every plug and noticed that number 7 and 8 cylinder plugs had black oil around their threads although the sparking tips were clean. No. 7 was some darker on the tan/brownish part above the spark gap. The compression when the engine was cold was showing practically equal at about 125 psi at cylinders 5-8. How accurate is the gauge is unknown but this doesn't seem too bad for an engine with so few miles on it after rebuild. Cylinder plugs 1-6 had no oil on their threads and looked pretty clean to me. My question about all of this is does this mean that I have a problem with the rings that will require me horribly pulling and dis assembling the engine again, could this be some kind of leakage of the intake manifold letting oil seep in because I used the cork front and back gaskets instead of running a bead of sealant or is there seepage coming in from the valve guide seals which were replaced when my heads were resurfaced? Of course I wake up at night tossing and turning thinking about this situation hoping that the engine still should be given more time to break in or am I damaging it by driving it like this. Is there any real way to know what's going on here or should I just keep driving it and hope it clears up? Many thanks in advance for any thoughts and suggestions you folks might have.

[techinspector1]

Since the motor is oiling on 2 cylinders only, my inclination would be to suspect either valve guide seals for those cylinders or maybe a breach in the intake gasket(s), allowing oily vapor from the crankcase to be drawn into those 2 cylinders when their intake valves are open. Either problem is not going to fix itself. I'm not telling you what to do, but if it were my motor, I'd be gettin' my tools out. Wait and let some of the others on this forum chime in, maybe someone has a better idea.

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[69Bee]

If the heads were not perfectly leveled when they were milled (or milled too much), in conjunction with using the cork end seals, it is plausible for the intake to suck oil. There are also a few other things that could do this; leaking (dislodged positive) valve seals, guides too loose, valve stems out of spec. The least expensive would be to reinstall the intake manifold, and use sealer instead of the cork end seals. The sealer will seal better than the cork, as the cork could stop compressing if the gap is too small, and not allow the intake to completely seal. Myself, I use Permatex Ultra Grey.