Out-of-the-Box PerformanceThe Brodix-HVH heads represent something else that is becoming the norm in cylinder head technology: For all intents and purposes, these heads are race-ready right out of the box. Brodix casts the heads at their own foundry, using 356 aluminum, and then heat-treats them to a T6 condition. Cylinder heads such as this are designed with revised spark plug locations, incorporate decks with a minimum thickness of 9/16-inch, and include heavily reinforced rocker stud bosses. Aside from being CNC-ported by HVH (with impressive flow figures to match), these heads include threaded inserts for the rocker studs, providing superior strength and durability. The seats are hardened (which means you can use unleaded fuel, but that's another topic) and cut on Serdi equipment. The guides are bronze-walled. The combustion chambers are fully machined.
In the case of the big-block Chevy heads shown, they're designed to accept a set of 11/32-inch stem stainless steel valves (2.25-inch diameter intake; 1.88-inch diameter exhaust). The intake valves are 0.250-inch longer than stock, which allows the use of any number of aftermarket springs (pockets are cut for 1.54-inch-diameter springs). Because of the longer valve stem and, consequently, the greater installed valvespring height, pushrod length must be checked when these heads are installed on an engine. Both Brodix and HVH recommend the use of two-ring positive seals for 11/32-inch valve stems and 0.531-inch guides. The rocker studs are 7/16-inch examples, which are fully machined. You can use a common aftermarket roller rocker or a shaft arrangement from Jesel.
When all is said and done, what's the point? It's simple: When searching for heads for a given Corvette engine combination, think less is more. Sure, big ports equal big flow, but at what cost? No matter what cylinder head you chose, the idea here is to balance the flow with port volume and couple with high-flow velocity. You'll get throttle response, gain torque, and the Corvette will most likely be a whole bunch more fun to drive. It works for us. CF