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81 a15 headers


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A stock engine usually has an exhaust manifold not a header. A header is a rot rod term for a home made exhaust system usually with thinner equal length pipes that improve on the sometimes restrictive stock system.

 

You don't know what those pipes do right? One is almost certainly the AIS. (air injection system) It uses exhaust pulses which are a pressure followed by a vacuum wave into a pipe connected to the air filter. There is a one way valve that only allows air to be sucked in on the vacuum pulses. This air is added to the exhaust and helps the cat burn off any hydrocarbons. The system is totally benign in operation as it works on the exhaust after it leaves the engine. If it fails the engine will never know it. If you must, pull the pipe and close off the hole with a pipe thread plug.

 

The other is likely the ATC. (air temperature control) this system uses warmed air from the exhaust manifold and cool air from in front of the rad and mixes them so the engine runs in a tightly controlled range of air temperatures. Your vehicle will run smoother, get better mileage and be easier to drive in all weather. The ATC eliminates carb icing in cold weather.

 

Easier to just leave these two things alone. The engine does not make more power without them.

 

The stock manifold flows just fine and a header isn't needed unless you add a large cam, port the head, larger valves, multiple carbs. In order to be worth any power they have to be an improvement over what's on there now. They are expensive, noisy, leak, come loose, rusty, wear out in a couple of years, don't fit, pain to install and worst of all never live up to your expectations. If you just have to have a header be sure not to throw away the stock manifold. You may be looking for it in a couple of months.

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