Premium Hemi heads with Boss-style valve covers and Jesel rocker system for small-block Fords.

Hemispherical-style combustion chambers have earned a formidable reputation for power generation. How did this come about? The Hemi head broke fresh ground in several areas, including skillfully uniting superior air flow with larger valves.

Generally, Hemi head valves are placed across the head compared to Wedge head valves, which are placed more longitudinally along the head. As a result the Hemi air flow route is easier, it has fewer bends, and the transfer of incoming and outgoing gases is more efficient. Also, the Hemi head usually employs larger valves because they are naturally inclined in their hemisphere and hence open toward the center of the cylinder. Their operation, therefore, generates freer air flow—not shrouded— resulting in easier cylinder filling.



Greg Brown

Greg Brown’s new company, Hammerhead Performance Engines, is entering the final stages of production of unique Hemi heads for Fords.

By some margin it is the most important news for small-block owners in several years. Indeed you might gauge it more notably than this.

With an emphasis on completeness, the innovative head kits will include cast aluminum Hemi-style valve covers, a Jesel 1.7:1 ratio rocker system and all the necessary valve and spring assemblies as well as gaskets.

The aluminum head kits can be directly installed on all small-block Fords: 289, 302, 351W and, with some modifications, even 351C engine blocks. As you might expect there is more than one dimension to the introduction of this new technology.

DSC_6739-webFollowing two years of development and testing, all of the mechanical details are now available. Importantly, the heads will accept any current or existing intake manifold for the designated block, thus a 351w intake will operate on 351W block. In the interests of efficient air flow, the intake ports are raised to present direct air flow to the valves. China wall spacers and lifter valley cover are supplied as are FelPro 1262R gaskets that provide the interface.

Within the 62cc combustion chambers, which facilitate pump gas compression when needed, reside stainless steel intake and exhaust valves of 2.200in and 1.650in respectively. Featuring 11/32in diameter stems the intake flows almost 400cfm; the exhaust 275cfm. The installed height of the valves is 1.950in which allows high lifts of around 0.800in and valve angles are set at 15 x 6 degrees for both intake and exhaust. While Beehive valve springs are supplied as standard for hydraulic roller applications, the heads will accept springs with a maximum of 1.500in OD.

DSC_6729-webTo its credit, no grinding is required of the block for exhaust pushrod clearance. In addition, it uses virtually any Windsor-style head gasket. The exhaust flange, which employs the Yates C3 bolt pattern, uses FelPro 1433 gaskets. Valve cover gaskets are of Flatout origin.

If you were asked about the single cleverest aspect of this new Hemi head kit, you might point not to its deck thickness of 0.700in to encourage safe use of power-adders or its full water jackets for proper cooling. You might also bypass its accessory bolt holes for the provision of factory components and its use of ARP 254-4311 head studs and point instead to its pricing.

First deliveries of the new Hammerhead Hemi head kits are expected to begin around late November or early December at a price of around $5,995 for the complete kit. Its public debut is scheduled for the PRI show where it can be viewed and discussed in the World Products booth #1343.



Hammerhead Performance Engines
Snellville, Georgia
(678) 570-0874