Heat Riser

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[TD=colspan: 2]I took off my exhaust manifold to replace it and noticed a flap that restricts the exhaust. What purpose does that have ? Seems to me it would be better if there was free flow for the exhaust. Would it hurt anything if i cut that flap out of there?[/TD]

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I'm prtty sure that flap you're decribing is for when the car is started when it is cold. Similar to a spring loaded choke on a carburetor it should have the same sort of spiral spring on the outside of the manifold. If memory serves correct it helps the car engine to warm up more quickly in cold weather. It probably won't hurt to take it out. the car might run a little rough at first then be fine after it's warmed up.

In theory, the hear riser valve closes when cold, forcing more exhaust thru the intake manifold cross over. This aids in cold warm up (heat under the carb), and allows the engine to come off the choke sooner. They are known to stick closed when left to sit. If you don't drive the car a lot in cold weather, lot of people remove them. If you can get the butterfly off it will appear stock. I usually find steel plugs to drive into the shaft holes, and plug them.