BluePrint Engines recommends the use of performance exhaust gaskets on all of our performance engines. DO NOT use the stock replacement type exhaust manifold gaskets. These are designed for original iron heads with iron exhaust manifold use only. They will not seal when headers are used. This is especially true when the engine has aluminum heads with headers. The stock type gaskets will blow out very quickly and cause exhaust leaks. This can eventually cause engine failure that would not be covered under our warranty. EXTREME IMPORTANCE FOR AFTERMARKET EFI SYSTEMS This is extremely important when using aftermarket EFI systems. They rely heavily on an accurate air/fuel mixture reading that is constantly monitored by their wideband Oxygen, or O2, sensors. An exhaust leak can cause a false “lean” condition by allowing unwanted oxygen into the exhaust stream. Once the O2 sensor detects this lean condition, it will adjust the air/fuel ratio to a richer mixture to compensate for the lean condition it is reading. Typically, the first signs of this problem will be fouled spark plugs, and/or a poorly running engine. RECOMMENDED HEADER GASKETS The first thing to remember is that you should always use header gaskets that match the shape of tube design on the header flanges. DO NOT use header gaskets to match the exhaust ports. Failure to do this will cause header leaks. Headers do not have to match the shape of the exhaust ports. On a street engine operating from idle to 6,000 rpm, you will not lose any horsepower. BluePrint Engines recommends several different types of header gaskets. Perforated steel core laminate type from Fel-Pro and Mr. Gasket. MLS, multi-layer steel from Percy’s and Kook’s. Copper gaskets from Cometic, SCE, Mr. Gasket, Summit Racing brand, and other brands. INSTALLATION TIPS Prior to installing your headers, verify that they are not warped. There is not a header gasket that will cure a warped header flange. Be sure to thoroughly clean all old gasket material before installing headers with new gaskets. Most exhaust gasket failures are caused by header bolts loosening and/or the gasket relaxing after several heat cycles. To help prevent this, replace old header bolts with the locking style bolts. 3/8” exhaust bolts are torqued to 25 ft lbs. 5/16” torque to 18 ft lbs. Use anti-seize on the bolt threads before installing the bolts. Recheck torque on all exhaust bolts after the first 50 miles, and again after 500 miles. Re-torque as needed. LOCATING EXHAUST LEAKS AT THE CYLINDER HEADS Often times exhaust leaks are small enough that they are often hard to hear when the engine is idling. They will also sound very much like a lifter ticking or a valve out of adjustment. Some can only be audible when the engine is under load. While a mechanic’s stethoscope can be used to locate many engine noises, they do not work as well for finding an exhaust leak. Since exhaust leaks are just air leaks, locating the source of the leak can be accomplished very easily by using a 2 or 3-foot length of vacuum line as a stethoscope. With one end held up near the ear, move the other end of the hose around the edge of the header flange, or exhaust manifold as this is where leaks are the most common. The minor exhaust leak will be easily heard and you will be able to locate the source of the leak within a square inch. If you cannot locate the source of the leak at the header flange, then check around the collector to exhaust pipe location. Over time, headers can start to leak where the four primary pipes are welded into the collector. Once the source of the exhaust leak is found, follow the steps previously explained in order to remedy the problem.