Cylinder heads, also known as "heads" sits above the cylinders on top of the cylinder block. Cylinder heads close in the top of the cylinder, forming the combustion chamber. Northern Auto Parts carries both stock replacement and high performance cylinder heads. If you are looking for stock OE replacement heads, take a lot at our Hilix cylinder heads and ITM cylinder heads. If you want performance, Edelbrock, RHS, and WorldProducts cylinder heads can't be beat.