Dave Mackie Harley-Davidson Hi-Flow Heads
Complete Head Porting and Contouring Services
It's difficult to photograph our special shapes and contours. We have tried to show you samples of the finished product and let you judge for yourself. What we strive for

Headwork
Valve Job Only: Includes complete high-performance valve job, setup, and assembly. Prices for cam with extreme lifts may be higher - contact us for details.

Porting Only: Includes compete porting and contouring, polishing of the combustion chambers/exhaust ports, and high atomization intake ports.

Complete Headwork: Includes porting, contouring, flow-testing, complete high-performance valve job and assembly (less rocker arms).

Separately provided services include:

• Cylinder boring and honing
• Replace valve seats (for use with leaded or lead-free gasoline)
• Counter bore for Big-Bore cylinders
• Dual-plug Shovelheads
• Dual-plug Sportsters
• Dual-plug Evolutions
• Head surfacing
• Compression Releases

Custom Headwork by Dave Mackie Engineering
For decades Dave Mackie Engineering (DME) headwork has been ranked with the best available anywhere. The Keith Ruxton engines in the Easyrider Streamliner were running DME ported heads when it became the World's Fastest Motorcycle at over 322 miles per hour. Bob Taft of Rat's Whole Place was running DME ported heads when his dragbike became the World's First 8-Second Evolution-Powered Dragbike. The list goes on to include scores of national records, many National Championships and Sturgis and Daytona Dyno Shootout Winners, and very Streetable Twin-Cams with 105-115+ HP.

DME headwork has several features that make it unique in the industry. Our competition valve jobs, coarse texture, high atomization intake ports, selective use of polishing, and the use of top-of-the-line premium parts yield the most efficient heads available.

First let's discuss polishing. There are several conceptions about polishing ranging from "it's magic" to "it doesn't do a thing." The truth lies somewhere in between. Polishing actually melts and seals the skin of the surface being polished, thus forming a bit of a barrier to help retain heat in that area. At DME we polish the combustion chambers and the exhaust ports. It is desirable to keep heat in the combustion chamber because heat is power, which is what we're after. We also want to keep heat in the exhaust ports because the hotter the exhaust gases are the greater the velocity they will have. Increased velocity will get the gases out faster. The benefits still exist even after these areas carbon up because the underlying surfaces are still sealed.

Areas that should not, in our opinion, be polished are the intake ports and manifold. Polishing has little or no effect on flow characteristics but it can have a detrimental effect on atomization. The reason for this is that the fuel in the intake charge is heavier than the air. When the charge bends its way through the manifold and port, the fuel tends to centrifuge itself out of the airstream and onto the port wall. When the wall has a high polish the fuel tends to cling to the wall and slides on into the combustion chamber as raw fuel. Raw fuel does not burn as well or as completely when atomized and this can result in less power, less economy, and a "dirtier" motor. For these reasons DME creates very coarse texture, high atomization intake ports and manifolds. This coarse finish inhibits the sliding of the fuel and "kicks" it back into the airstream where it is then re-atomized. This can result in more power, better economy and a cleaner running engine.

DME competition valve jobs are done on state-of-the-art Sunnen and Kwik-Way equipment to ensure we get the most concentric and accurate results possible. Our valve jobs may have as many as six angles, or be fully radiused, or a combination or angles, radiusing, and blending by hand depending on the effect we're trying to create.

At DME there is no such thing as "one size fits all." We make every attempt to customize each set of heads to the individual needs of the customer.