63dartman
Well-Known Member
98 360 pre magnum with kb107 pistons, Are the black rings at the top edge of the bore normal? If not any ideas what would cause this?
thanks Treblig! I decided to block the oil holes for the shaft mount rockers since I'm running magnum heads with pushrod oiling and saw this. Thanks for the "peace of mind"Normal. The top ring in 1/4" to 5/16" below the top of the piston so some of the combustion gases (and exhaust gasses) will leave deposits in the area that is not used by the rings. There is always a space between the piston and the bore so the carbon build up will always be seen in that area.
thanks Rusty.That's the unworn part of the cylinder called the "ridge". It turns black with carbon, because the rings don't ride that high and keep it clean.