How to Replace Head Gasket on Chevy 350 Engineby John Stevens J.D.
The 350 is quite possibly Chevrolet's most popular small-block engine. Although the 350 is known for its durability, this does not mean that the engine is always problem-free. A blown cylinder head gasket is typically caused by overheating, and results in a substantial loss of power and the harmful mixing of antifreeze and engine oil. Replacing the head gasket may initially seem like an arduous task, but on the Chevy 350 the process is much easier than on many other types of engines.
Remove the carburetor and distributor from the top of the intake manifold. The carburetor is attached to the intake manifold with four nuts. One nut is at the base of each corner of the carburetor. Remove the four nuts with a wrench, then lift the carburetor away from the intake manifold. The distributor is held to the intake manifold with a single bolt at the base of the distributor. Remove the nut with a wrench, then pull the distributor straight up to remove it.
Drain the radiator and disconnect the upper radiator hose from the intake manifold. Loosen the single bolt at the bottom of the radiator on the driver's side to drain it. The upper radiator hose attaches to the front of the intake manifold with a hose clamp, which features a single screw. Loosen the screw with a screwdriver, then pull the hose away from the intake manifold.
Remove the intake manifold, the exhaust manifold and the valve cover. The intake manifold attaches to the engine with four bolts on each side of the manifold. Pull out the bolts with a wrench, then lift the manifold off the engine. The exhaust manifold attaches to the side of the cylinder head with six bolts. Remove those bolts with a wrench, then pull the manifold away from the engine until it disconnects from the cylinder head. The valve cover attaches to the top of the cylinder head with four bolts. Remove those bolts and pull the cover off the cylinder head.
Loosen the eight rocker arms, then remove the eight pushrods and the cylinder head. Locate the single nut in the middle of each rocker arm. Loosen the nut on all eight rocker arms until the tip of each rocker arm can be twisted away from the top of its pushrod; then pull the pushrods out of the engine. Using a wrench, remove the 17 bolts that secure the cylinder head to the engine, then lift the head off the engine. Remove the old cylinder head gasket.
Place the new cylinder head gasket onto the head's mating surface on the engine block, then lower the cylinder head onto the gasket. Do not apply gasket sealer to either side of the head gasket. Install each of the cylinder head's bolts, tightening each bolt only in small increments to ensure that the gasket seats evenly. Slide each pushrod through the cylinder head, then position the tip of each rocker arm over its pushrod and tighten the rocker arm's bolt.
Install the valve cover, exhaust manifold and intake manifold. The valve cover must be installed with a new gasket. Coat both sides of the gasket with gasket sealer, then place the gasket along the lip of the cover. Lower the cover onto the cylinder head, then install and tighten each of valve cover's four bolts with a wrench. The exhaust manifold must also be installed with a new gasket, but gasket sealer must not be used. Bolt the exhaust manifold to the cylinder head with the new gasket. The intake manifold uses four gaskets, all of which must be covered with gasket sealer. Place the coated gaskets onto the engine, then lower the intake manifold onto the gaskets and install the manifold's retaining bolts with a wrench.
Connect the upper radiator hose to the intake manifold, and fill the radiator with antifreeze. Slide the distributor into the engine through the intake manifold, then secure the distributor in place with its single retaining bolt. Place the carburetor on top of the engine, then install and tighten each of the carburetor's four retaining nuts.