W-series Cyl Block Changes
Six new water galleries were added at the exhaust side of the cylinders. NOTE: The "W" engine bare block will NOT be stamped with a "W". Check for additional water galleries to identify a modified bare block.
In addition, the oil pan bolt holes have been altered in the modified cylinder block. The holes have been chamfered to allow usage of a liquid oil pan gasket. These chamfered bolt holes are also helpful in identifying the modified bare block.
Sources Used on This Page: 1988 Nissan 300ZX Factory Service Manual, Nissan Technical Service Bulletin Number TS87-191 Date: December 28, 1987