redneckjeeper wroteKillahxft_jeep, gschuld hit the nail right on the head, :!: his explaining that butterfly in the exhaust is probably the best way to explain its operation. And there is not a delete part to go in its place, all you will have to do is shorten the exhaust studs and put the exhaust donut (gasket) on the pipe and mount it right to the exhaust manifold.. These exhaust butterflys were a very popular used on the older chevys and did do there job until the spring broke and would always flap and make noise when the engine was running. In all my 35years of working on vehicles I have probably removed 100's of them because of broken springs or the butterfly would stick closed or stay wide open.. :t:
Yeah, I always knew them as "heat risers". Used to wire them open because like redneckjeeper said, they'd always rust and stick. Their job was to send hot exhaust up thru the intake manifold crossover to help warm up the engine. They had a thermostatic spring that let them open when it got so hot.
Fuzz, definitely not an Air Injection Reaction (AIR) system like shown in your picture. It was located up high, at least as high as the steering pump, and to the rear and further toward the driver's side from it.
