How to Assemble Cylinder Heads

Before You Buy
To make your cylinder head experience a pleasurable and effective one, you should consider a number of factors before actually purchasing anything. Here's an overview of some of the things you should be conscious of prior to placing your order.

The Intent: It may sound overly obvious, but Mike Johnson of JMS Racing engines advise us that way too many people he encounters shop for speed parts with a bigger-is-better mentality. With the high level of performance that much of today's aftermarket hardware is intended for, it's easy to select parts that are simply overkill for a lesser project. In the case of cylinder heads, the general rule is, as the intake runners and the intake valves get larger, the powerband moves higher in the rpm range, and low-end power usually suffers. Displacement, compression, camshaft, and intended rpm range use need to be established before buying.

Compression: Many people think only the pistons determine compression, but with many engines, the primary variable is the combustion-chamber volume. Determine your desired compression first, investigate the available piston designs for your engine, and then select your ideal chamber volume.

Camshaft: Determine what type of camshaft you plan to run (hydraulic, solid, roller, etc.), and have at least a rough idea of the actual lobe specifications before ordering heads. The cam should complement the cylinder head choice, working to utilize the potential of the ports while being compatible with other factors like compression. Valvesprings will be selected based on the cam type and grind, which may have an effect on the size of the spring seat, the height of the valve-guides, and even the type of valve seals used. Piston-to-valve clearance must also be considered.

Supporting Hardware: Don't sell your soul for a set of trick heads without first determining if you can also afford the required hardware to make them work. For example, many high-performance heads are designed for specific aftermarket rockers or valves; some require special intake manifolds, and some may have relocated exhaust ports that will require new headers. Know what you're getting into ahead of time.

Who Is Pro Topline?
The topic of this story is assembling heads, but the examples shown are high-performance small-block Chevy castings from Pro Topline. While that name may still be unfamiliar to many street machiners, the racing industry is already well-acquainted with Pro's wares, with noted engine builders like Ronnie Shaver and Ken Duttweiler enjoying wins in circle track and drag competition using its products. What may come as a surprise is that while Pro Topline specializes in performance heads for small-block Chevy, Ford, and Chrysler engines, as well as big-block Chevys and Fords, the company is actually based in New Zealand. The organization was founded over 30 years ago by president Craig Pulman, who, after tiring of having to extensively modify existing manifolds and heads to gain the performance he sought, decided to start making his own. By 2001, the original company, Pro Action Cylinder Heads, merged with Topline Automotive Engineering, resulting in the Pro Topline name along with 500,000 square feet of manufacturing facility using the latest technologies to produce world-class performance products. We'll be dyno-testing these heads soon, but you can check them out in the meantime at www.protopline.com.