Angling For Power
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The stock exhaust valve in the middle is a typical OEM valve. The valve on the left is a Vortec piece that incorporates the 30-degree back cut. The valve on the right is a Manley stainless steel piece. We found a 15-cfm gain at 0.400-inch lift on a Vortec head with the 30-degree back cut on an exhaust valve, which is why the heads now come that way from the factory. View Related Article
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