Chevy SB Cylinder Head ID Guide - Free download as PDF File (.pdf), Text File (.txt) or read online for free. This document provides a guide to identifying Chevy small block cylinder heads by their cast marks and numbers. It lists the cast marks, numbers, descriptions, and production years for 20 different Chevy small block cylinder head castings (A through P). It also lists the top 10 production Chevy small block cylinder heads and provides details on their chamber sizes, valve sizes, ports, and other characteristics. Location of date codes on the heads is also specified.