If the engine has been removed from the car, disregard the following steps which do not apply. For vehicles equipped with air conditioning, carefully examine the routing of the NC hoses and the mounting of the compressor; depending on the exact system used, it may be possible to remove the exhaust manifolds without disconnecting the NC system, but if in doubt, consult a certified dealer or refrigeration specialist to have the system depressurized, and do not disconnect the NC hoses while under pressure. Begin by disconnecting the negative battery cable and the carburetor hot-air pipe routed from the right exhaust manifold to the air cleaner. Mark each spark plug wire with a strip of coded tape (numbered 1-8) before removing them, ensuring to pull on the rubber boot and not the wire itself to avoid mixing up the order. Remove the spark plug wiring heat shields, which are held in place with a bolt into the engine block, and disconnect the rubber AIR hoses where they meet the manifold check valves, allowing the single metal pipes and the AIR manifold to be removed with the exhaust manifold. If equipped with power steering or air conditioning, remove the brackets attached to the left side manifold, then disconnect the exhaust pipes from the manifold flanges, hanging them from the frame using wire. If bolt locking strips are present, use a screwdriver to pry them away from the exhaust manifold bolt heads to enable the use of a standard wrench. Remove the exhaust manifold end bolts first, followed by the center bolts, and lift the manifold with its AIR injection tubes away from the engine. When replacing the exhaust manifolds with new ones, transfer the carburetor hot-air stove and the AIR injection tube system. Before installing the new exhaust manifolds, clean the mating surfaces on the cylinder heads and exhaust manifolds, ensuring all leftover gasket material is removed. Place new gaskets into position on the cylinder head, using a thin film of sealer to hold them in place, then install the manifold and torque-tighten the center bolts first, followed by the end bolts, noting that on some models it may be best to install the left rear spark plug heat shield first due to inaccessibility after the exhaust manifold is in place. Reinstall the remaining components in the reverse order of removal, using a new gasket or packing at the exhaust manifold-to-exhaust pipe flange. Finally, connect the spark plug wires according to the coding for the correct firing order, which can be verified by following each wire to its location on the distributor cap, ensuring the proper order in a clockwise rotation around the cap is 1-8-4-3-6-5-7-2. Start the engine and check for exhaust leaks where the manifold meets the cylinder head and where the manifold joins with the exhaust pipes.
Posted by GMPartsGiant Specialist 
