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The stainless valves are from SI, and measure .100-inch longer than stock, with valve head diameters of 2.145-inch on the intake side and 1.81-inch on the exhausts. The Indy chambers only needed a minor amount of work to achieve the size and shape Nelson was after. Note the unshrouding around the intake valve, and the encouraging of a kidney bean or heart shape to the chamber. Nelson has trusted Richard Reymer (of West Coast Cylinder Head) to work over his castings. The target flow numbers are 365 cfm on the intake side and 240 cfm on the exhaust side, when flowed at 28 inches of water with the valve at .600-inch lift.