How to Install Small Block Chevy Headsby Don Bowman
When installing a set of heads on a Chevy, the surface preparation is important to prevent leaks. The surface on the head and the block must be free of gasket material, dirt, dust and all grease. If the heads are not new, they should be checked for cracks, warpage, valve condition and seating, valve guide wear and spring tension (at the machine shop). The head gasket should be handled with care so there are no bends or dents that would cause poor sealing.
Wipe the block and mating surface of the head with alcohol or carburetor cleaner to remove any remaining grease or oil. Make sure that there are two locating pins in the block on each side and make sure they are seated completely.
Install the head gasket with the right side up and all the way down on the locating pins. Some head gaskets can be installed either side up. If the head gasket cannot be installed either side up, the right side will have the word "UP" on it.
Install the heads carefully, locating them on the locating pins. Install the head bolts using a washer under the head bolt if the heads are aluminum. The short bolts go on the lower side of the head below the exhaust manifold. Spread some RTV silicone on the threads of the small bolts prior to installation. They enter the water jacket and could leak without the sealant. There are three sizes of head bolts, so make sure they are inserted in the right holes.
Tighten the bolts loosely using the ½-inch ratchet and a socket. It is very important to tighten the bolts in a sequence so the head does not warp. Start in the center of the head and then move to the next bolt on the lower left side, to the high bolt on the right side and so on. Make an X pattern starting from the middle and working outward to spread the torque out.
Torque the head bolts in the same manner in three stages. Start by tightening all the bolts in sequence to 45 pounds of torque, then to 75 and finally to the torque recommended. Depending on the type of head you are installing, the final torque number will be different. If you do not know what the final torque is, call a local machine shop for this information (this is common when you buy used heads---the instructions do not come with the heads). You will need to provide the year of the engine and the type of head you purchased.
- close Do not assume that the standard Chevy torque sequence is the same for all heads. Camel back heads, stock heads, aluminum heads and all other types of heads have different torque sequences. Also, if you have torque to yield bolts instead of standard head bolts, the torque sequence may be different.