Cylinder head dowel to locate cylinder head and gasket on block. This is the dowel that locates the cylinder head on the block of the AJP V8 and Speed 6 engine and also references the head gasket. There are 2 per engine. In the Speed 6 engine the longer cylinder head bolt TVR E6022 10MM should be considered in these positions as the dowel reduces the available thread and hence the 2 dowel locations are the most likely to strip the thread on a rebuild or head gasket replacement. The AJP V8 has 2 per cylinder head so 4 in total.