[wl_walker]

I have a 1960 C10 short step side with a 350 ci motor. Block code indicates it's a 1969 and is a 4-bolt main. Previous owner had the motor 'refreshed' which means just that the seals were redone most likely. No1 and 7 cylinders have oil intrusion and is fouling the spark plugs almost immediately. All cylinders are showing 155 to 160 compression. I also have a rattle sound from under the hood that seems to be valve train, only hear it when at speed over 45 mph. New plugs, plug wires, rotor and cap. My thought is this: I'm hearing the valves rattle in the guides, oil is entering at the valve guides, time to pull the heads and have at minimum the guides and seals done. I don't expect a diagnosis, just a friendly discussion about past experience and possibilities...

EDIT: I also have a bit of smoke coming form the crankcase. When I remove the PCV I see it. Might be combustion in the 'bad' cylinders pushing past the intake guide after the exhaust valve closes?