If the car has A/C be very careful with the A/C hoses and the position of the compressor, as it is many times possible to take off the exhaust manifold without affecting the A/C system, but if there is any doubt take the car to a GM dealer or a qualified mechanic and take the pressure off the system and do not disconnect any A/C hoses with pressure on them. First, eliminate the air cleaner and the carburetor pre-heat tube if present, second, eliminate the front engine strut that is installed between the radiator support and the
Cylinder Head. First, unbolt the engine oil dipstick tube on the left of the exhaust manifold, and the exhaust sensor on the side of the exhaust manifold. Next, remove the A/C compressor mounting bracket provided at the centre of the exhaust manifold as well. That identifies the positions of the four spark plug wires, removes them and suspends them at the side to afford room for working. Remove the exhaust pipe nut connecting to the exhaust manifold and suspend it with wire to the frame. First, take out the end bolts of the exhaust manifold, then the center ones, after that, exhaust manifold as well as gasket. As a prior to fitting a new exhaust manifold clean the surfaces on the cylinder head and manifold that comes in contact with the gasket where there should be no leftover gasket material. Install a new exhaust manifold gasket on the cylinder head of the engine and fit the manifold in position, tightening the manifold nuts to only as far as was comfortable with your fingers. Turn the manifold mounting bolts slowly in a progressive manner until all get to the required torque. Last of all replace all components in reverse order with new gaskets where required cranking the engine and checking for exhaust leaks at the joint between the manifold and cylinder head, and the manifold and exhaust pipe.