If one were to dissect the Pontiac enthusiast community, the disciples of the brand can be put into a few different groups. For example, some find favor with a perfectly restored numbers-matching Pontiac while others are desirous of an all out race car—and there are many tastes that come in between those extremes. A gamut that wide makes HPP an interesting magazine, since it needs to cover all aspects of Pontiac ownership.
A Clear Picture
Every internal combustion engine can be considered nothing more than an air pump. The more air that can be packed into the cylinders with the proper mix of fuel, the more power the engine has the potential to make. Undeniably, the cylinder head is the key component in the recipe for horsepower.
When examining the cylinder head, the combustion chamber shape and size, along with the intake and exhaust port configuration, are key factors. Other areas are important, such as the valve size and angle in relation to the bore center and the spark plug location, again referenced from the center of the cylinder. For all intents and purposes, the enthusiast can only modify the port shape, while the other factors are design elements.
 Blu-Sil comes in two separate tubs, and when mixed together, has the appearance of a t
Porting of the cylinder head is the key to optimizing airflow for that casting, and as with most things, can be done to the level you desire—you can do as much or as little as you want with a corresponding gain in power. The key to porting a cylinder head is to remove or re-contour the material where it will improve airflow and port velocity. The speed of the incoming charge (air and fuel mixed together) is paramount in achieving a high level of cylinder fill that is identified as volumetric efficiency. An individual who goes in a port and just starts grinding is akin to being blindfolded while shooting at a target. It is possible to hit it but the probability is very low.
Within the industry it has been determined that the valve angles and the bowl of the port (the area just above the valve seat on the runner side) pays the greatest dividends when looking to improve airflow. A production-style cylinder head probably does not exist that will not see a dramatic flow increase with a blended bowl and high-quality multi-angle valve job, which has the seat cut and not ground into shape (Note: Many in the Pontiac community have not embraced the benefit of using a cutting bit to form the seat angles in lieu of the traditional method of employing stones to grind the seat. For more on this, reference the April ’12 issue, “Project Pure Poncho: Porting and Machining the Cylinder Heads” or online at http://www.highperformancepontiac.com/tech/hppp_1204_porting_and_machining_cylinder_heads/. If you want more airflow after that, the runner and complete port will need to be worked.
 These are the complete molds of the already-ported 6X and the unported Edelbrock D-por
A problem with reworking a port, even for the most experienced head porter, is that you cannot really see what is going on. Looking into the port from either side can show some of the area, but you are guessing at the true shape of the majority of the passage. The best method of attack then would be to have a sacrificial cylinder head that can be placed on a bandsaw and cut in half, exposing the intake and exhaust port. Now you can formulate a proper plan since the flow restrictions and obstacles are in clear view.
The reality being it is not practical—or in many cases, even possible—to have an extra cylinder head laying around to cut in half. Also, what if you want to compare ports before you make an investment, you cannot go around cutting everything in half—there has to be a better and more practical approach. Port molding is the answer.
Making An Image
Though there may be some debate as to when the practice of making a mold of the ports came about, Bob Wells of Perma-Flex Mold Company tells HPP that to the best of his recollection, the Chevrolet Division of General Motors first did this using the Perma-Flex molding rubber sometime in the ’60s. It seems that Perma-Flex was and still is a supplier to GM for a variety of molding and other materials. The engineers faced the same problem as the Pontiac enthusiast when wanting to examine a port. Thus, someone at GM came up with the idea of employing a method that was already used in other aspects of development for a variety of parts—they made a mold. The Perma-Flex Blu-Sil silicone rubber is the material of choice to make a mold of a Pontiac cylinder-head port or that of an intake manifold runner.
 The combustion chamber shape of the two different cylinder head designs is apparent, a
Blu-Sil is a two-part product that needs to be mixed just prior to pouring it into the port of the cylinder head. It retails for $163 plus shipping, and includes enough to make a mold that displaces the volume of one gallon—you can make many port molds with the basic investment. Please contact Perma-Flex Mold Company for exact specifications and mixing procedures for its product, along with a suggested release agent, such as petroleum jelly.
Deciding on what area of the port you want to study will determine the mold that you make. For this primer, HPP used The Mule’s well-modified 6X casting, along with the Edelbrock D-port cylinder head.