Performance & Hotrod Business February '14

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strate, which provides a cushioned support between the substrate and the converter case. The insulative and cushioning matting that supports the substrate inside the converter housing consists of a material called vermiculite, which is secured by a binding agent and a fiber mat. When the converter is assembled, the matting structure is installed in an unexpanded state. As the converter experiences its initial heating cycle, the fiber mat and binder burns off, and then expands. If sufficient time is not allowed for the material to expand, the matting becomes loose and can't expand to fill the cavity in order to support the substrate. This can result in the substrate vibrating and banging around inside the housing. If you hear a rattle noise coming from a converter, that's a sure sign that the substrate has loosened, in which case the converter must be replaced. Following a proper break-in procedure for a new catalytic converter will help to ensure long life. It's important to be aware of this need, to allow the matting to properly expand as it is exposed to heat for the first time. Once the complete exhaust system (including the converter) has been fully installed, start the engine. Run the engine at idle speed and allow it to gradually warm up. Do not rev the engine. After the engine has reached operating temperature, smoothly increase engine speed to about 2,500 rpm, and hold the engine at that speed for about two minutes. Then, smoothly reduce engine speed back down to idle and allow it to cool back to normal operating temperature. Shut the engine down and allow it to completely cool. At this point, the converter matting should have expanded to support the substrate, and you're good to go. Catalytic converters, in large part due to the expensive precious metals used in the substrate washcoat, are expensive components. In addition, if you pay extra for polished stainless steel, or invest the time to polish the housing on your own, it doesn't make sense to kill a perfectly good converter simply because it wasn't cycled properly. Mike Mavrigian has written thousands of technical articles over the past 30 years for a variety of automotive publications, in addition to writing nine automotive technical books for four different publishers. Mike also owns and operates Birchwood Automotive in Creston, Ohio, where he builds custom engines, street rods and performs vehicle restorations. Mike can be reached at 330435-6347 or Birchwood's website is WORLD'S BEST CUSTOM CAR COVERS® Choose from 14 High-Performance Fabrics also: • SeatSaver™ • UVS SunShades • DashMat® • Premier™ FloorMats • LeBra® • Colgan® Car Bra ...and much more and check out this fre and check out this free service... e servic e... Don't miss another sale. Sell Covercraft Products online, Seamlessly! CartLink™, powered by Covercraft Industries, Inc., is a seamless way for you to allow your web customers to look up any of Covercraft's vehicle-specific products and add them to their shopping cart without leaving your website. • We maintain your data so you always have the most up-to-date application information. • Seamless so your customer can get their pattern information and then add it to their shopping cart. Visit: for more information email: • • 1-800-4-COVERS (426-8377) February 2014 PHBFEB_52-77.indd 55 n Performance & Hotrod Business n 55 1/7/14 2:16 PM

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