Taking you back to last month where we assembled the short-block, a Bullet A-Fire cam fires a four/seven swap for a smoother-running 1-8-7-3-6-5-4-2 firing order, and pushes .808-inch of lift on the intake, and .782-inch for the exhaust. This requires Manley NexTek valve springs set up for 280 pounds of spring pressure on the seat. Utilizing Manley titanium retainers matched with 10-degree locks isn't an option; it's a requirement. The Manley stainless valves are a good choice for this motor. Matt feels they work well for the engine's upper rev limit of 8,000 rpm, they save some money compared to titanium, and they accept more heat in a nitrous application down the road than ti valves would . These intakes measure 2.400 inches in diameter, and the exhausts are 1.900 inches. During handling, the castings are placed on cardboard sheets to prevent scratching, which preserves the sealing surfaces.