One of the benefits of a CNC-machined...
One of the benefits of a CNC-machined cylinder head, such as this Motown Lite from World Products, is that the machining processes are all registered from a consistent point, so core shift variables are virtually eliminated. Courtesy of World Products
As it was with our cast-iron roundup, we are sticking with what is by far the most common option available for racers-the small-block 23-degree Chevy head. This time, however, we are dealing with as-cast and CNC-ported heads (when available).
Chevrolet's pickings are a little slim when it comes to aluminum heads for stock car racing. The head most commonly allowed by the rule books is the famous Fast Burn cylinder head. This is a fully machined head with dual bolt patterns for early-model and Vortec intake manifolds. Maximum valve lift is 0.530 without modifications.
Pro Action 23-degree SBC cylinder heads feature specially designed runners and combustion chambers (available in 50cc, 64cc, and 72cc volumes) to maximize volume, atomization, and velocity. Improved valve guide material yields tighter tolerances and extended durability. Available in aluminum or iron and straight or angled spark-plug configurations, Pro Action SBC cylinder heads accept 1.550-inch diameter springs and standard-style rockers and valvetrain.
PRO 1 aluminum cylinder heads for small-block V-8s deliver advanced airflow technology at a very good price. Options include four intake runner sizes (180 cc, 200 cc, 215 cc, and 230 cc), two chamber volumes (64 cc and 72 cc), five valve diameters, and straight or angled spark plugs. Hardened exhaust seats and long-lasting mag-bronze valveguides extend cylinder head life. They use standard small-block pistons, headers, and valvetrain components and are bolt-on replacments for most conventional 23-degree heads.
The Motown 220 Lite cylinder head from World Products is engineered for increased power, yet benefits from high-volume CNC manufacturing to keep prices in line with street heads. Some of the features contributing to the effectiveness of the Motown 220 Lite include intake runners with an improved short turn, optimum port consistency, and CNC-machined chambers. Cast from 355-T6 high-density aluminum alloy for added durability, all machining operations are registered off the combustion chambers to ensure proper centering over the cylinder. They are available bare or in complete assemblies.