exrodder 2 things come to mind, valve stem seals are damaged on assembly of the heads. If you have a compressor put air in the cylinder and replace the seals for these to cylinders. Do a compression test on all 8 cylinders, if the rings are not install right you could suck the
oil up though them. Do you have a pvc valve on the motor? What is the vacuum on the motor at idle? Poor valve guides could be the other choise. Pull the heads and have the guides miked and checked for rock or out of round. Are you sure that it is
oil and not fuel fouled? What color is the smoke? Black is fouling plugs and blue is burning
oil smoke normally. Start with the basics, what color that we go from there. Does the car have a miss or shake when this happens? Get back to us. Rick Lake