When installing the cylinder heads, they must be torqued down using a sequence specific to small- or big-blocks. Smeding uses AFR’s 325cc castings on its 572 crate motors, which flow a very impressive 384 cfm. They’re outstanding performers in street/strip applications, whereas anything larger is better suited for higher-rpm applications. On Gen I small-blocks, 200cc and smaller heads generally work very well in mild street/strip combos. Going any bigger in port volume requires a commitment to wind out a motor past 7,000 rpm, or building a 400ci-plus short-block.