On the left, the original CNC LS6 casting was milled to produce 65cc combustion chambers. The compressed gasket thickness of 0.038 inch produced 10.7:1 compression ratio. Intake valves are 2.05 inches; exhausts are 1.55 inches. On the right, the surface of the Scoggin-Dickey CNC L92 head was milled 0.030 inch to yield 65cc chamber. Valves are Manley stainless: 2.160-inch intake and 1.590-inch exhaust, the same size as stock. Both cylinder heads have a 15-degree valve angle.