Are 706 heads better than 862 heads?
Are 706 heads better than 862 heads? The 706Vortec heads are even slightly superior to the commonly found 862 heads. The reason is that the 706 heads are SPM (semi-permanent mold) made, while the 862 heads are sand cast. The SPM method is considered to be a more consistent process, but once you port the 862 head, any difference to the 706 head goes away. What should I look for in a cylinder head? For example, a cylinder head may deliver impressive numbers at .700-inch lift; however, a street engine doesn’t typically provide that much. It is more practical and...