The block bow tie cylinder head is the top-performing cast iron head in the GM line. The latest (Phase II) head is almost identical to its predecessor (the Phase I), but boasts a new outer water jacket wall. And unlike the Phase I bow tie, the Phase II is marked by machined bars between its manifold flanges.

The Phase II block bow tie also offers a redesigned combustion chamber with higher volume than that of the Phase I. At 64 cubic centimeters, the Phase II bow tie gives hot-rod racers added power and performance. But the Phase II also does away with the manifold heat riser passages characteristic of the Phase I head, creating a much denser (and cooler) intake charge.

Shop for a Block Bow Tie Online

As with most GM performance parts, the bow tie cylinder head is widely available online. Many auto buffs would rather inspect their bow tie's valve-spring pockets and pushrod guide plates, which is understandable. But there's a simple solution for those wary of buying "sight unseen."

Use the Web to suss out your options and compare dealers. Because the Internet expands your market options, consumers tend to enjoy the price breaks brought by stiffer competition. Once you find a vendor in your area who offers great prices and service, it's time to drive to the showroom or factory to buy your bow tie cylinder heads (or any other crate engine part) in person.