cylinder head

Cylinder Head

This section examines cylinder heads. The cylinder head bouts on the top of the of the cylinder block where it forms the top of the combustion chamber. In line engines of light vehicles have just one cylinder head for all the cylinders. Larger in line engines can have two or more. Vee type and horizontally boss engines have a separate cylinder head for each bank of cylinders. Just as with engine blocks, cylinder heads can be made of cast iron or aluminum alloy. A head made of aluminum alloy is lighter then if it was made of cast iron. Aluminum also conducts heat away more quickly than iron. So, with an aluminum alloy head the heat of combustion can be conducted away into the coolant more quickly.

Manufacturing the head is similar to manufacturing the block, a casting mold is made. Sand cores are put in to form any hollow areas. Depending on the engine this can be for coolant and lubricant passages and inlet and exhaust ports. Air-cooled engines have cooling fans cast into the cylinder head. The under side of the head is shaped to form the combustion chamber. Molten metal is poured in and allowed to cool. The cores of broken alloy are removed and the cylinder head cleaned of any sand. After casting comes machining, surfaces that must seal are machined flat. Holes are drilled and tacked for attaching bolts and stubs. In sand cast heads, the large holes that had contained sand are machined then fitted with soft metal plugs called core plugs.


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