How to Assemble Cylinder Heads

The crew at JMS advised that when running any cam with more than 0.450-inch lift, the installed height of the valvesprings and retainer-to-guide clearance must be checked. This begins by assembling the valvespring retainer on the valve without the spring. Using a dial caliper, the distance from the spring seat to the bottom of the retainer is measured with the valve on its seat. It's also a good idea to measure the distance between the valve seal and the retainer at maximum lift to make sure the two will not come into contact. The generally accepted minimum is 0.050 inch, though we had much more. If there's not enough clearance, the valveguides will have to be machined down to lower the seal.
The crew at JMS advised that when running any cam with more than 0.450-inch lift, the inst
If this were a stock production head, we'd be ready to assemble the castings at this point. However, since this is a performance application, there are a few more checks to make before putting everything together. The first is the spring-seat diameter. High-performance applications require high-performance springs, and for many engines, the diameter of the stock valvesprings is too small. Our heads are being installed with 1.437-inch od dual springs, which generally require the spring pockets of a production head to be machined to a larger diameter, but our Pro Topline heads are made with the larger seats.
If this were a stock production head, we'd be ready to assemble the castings at this point
The valvespring is placed in the valvespring testing rig and compressed to the same height that was previously measured on the head. The gauge on the tester gives the amount of spring pressure, which in this case would be the pressure with the valve on the seat. Stock small-blocks only need about 100 pounds of pressure on the seat, but JMS likes to see a minimum of 120 pounds for performance applications, which is what the Powerhouse springs produced. To be precise, the camshaft manufacturer should always be consulted for the exact specifications per the application.
The valvespring is placed in the valvespring testing rig and compressed to the same height

The next test determines spring pressure at maximum valve lift. This requires you to know what camshaft will be used. We used 0.500 inch as our spec, so the spring tester was used to compress the spring to that height, which showed 360 pound of spring pressure. At this point, you should also be watching for coil-bind, a condition where the coils of the spring actually contact one another when compressed. Our springs were right in line for our application, but again, the cam manufacturer has the final word on these specs.
The next test determines spring pressure at maximum valve lift. This requires you to know
One other item to check when running dual springs is the clearance between the inner spring and the valve seal. The inner spring was a tight fit to the rubber seal, which could potentially cause the seal to be yanked off the valveguide while the engine is running, resulting in lots of blue smoke out the tailpipes. To be safe, we upgraded to narrower positive-control seals.
One other item to check when running dual springs is the clearance between the inner sprin
Finally it's time to actually assemble the heads. Alvarez likes to lube the valves with white lithium grease for protection during initial fire-up. Motor oil also works fine, except it can run off the valve stems before the heads are installed, leaving the valves to operate "dry" until engine oil can reach them. Assembly is straightforward--compress the spring, install the retainer, and snap the locks into place off the valve stem. But whether you're using a pneumatic or a manual valve-spring compressor, make sure not to compress the spring assemblies too far, or you can damage the valve seals. Once the heads are assembled, check to make sure the springs are sitting squarely in their seats, and you're ready to bolt the new heads to your motor. CC
Finally it's time to actually assemble the heads. Alvarez likes to lube the valves with wh

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.

SOURCES
Johnson Machine Service (JMS) 724 E. Huntington Dr. Monrovia CA 91016	Pro Topline
Powerhouse 931 19th St. Bakersfield CA 93301 www.enginekits.com

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