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#1
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I have a set of 340 heads. Milled .060 and have 2.02 intake and 1.60 valves. Would enlarging the exhaust ports only be beneficial?
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#2
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Leave as much metal as you can on the exhaust port floor, particularly about 1" in from the exhaust manifold mounting flange. This will create a sort of dam to prevent the retrograde flow which is present in most small block late model heads. Basically, you just need to clean up and gasket match the exhaust ports. Most of your flow improvement is going to be in the valve bowl area and the transition from the intake ports to the bowl. First there's a bump in the roof near the opening. It can be completely removed. Then there's a need to widen the intake port where the pushrod holes are. Be very careful here not to cut through to the pushrod holes. Finally, smooth the contour from the intake port bowl to the valve seat and clean up bowls. Also make sure to remove the parting lines that exists in each bowl parallel to the deck surface. Wedgehead
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#3
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To answer your question I would say yes, but with a caveat. The as cast head is exhaust challenged. Porting the head usually makes this imbalance worse if you are good at intake porting. I would much rather see you start with the 360 high swirl heads (aka 308 castings). These have much better shaped exhaust ports that are actually smaller than the 340 head. The increase in flow is due to the better radius on the floor of the 360 head. That radical drop in the floor of the 340 exhaust hurts the flow and is difficult to make up for with porting. Shape matters!
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