IHRA rules mandate a manufacturer's crate engine. In the case of the Chevy 502, it's available in kit form, which means a bare block to begin the assembly. Although many components of the street-intended kit are replaced for this racing application, a surprising number of them are retained. McLaren overbored the engine .060 inch, even though IHRA allows a .070-inch overbore. The .060 job leaves room for a future rebuild.