Engineers at RHS have recently designed the only small-block Chevy 23-degree cast-iron head that is CNC-ported from the factory. The precision accuracy and durability of the Pro Elite SBC 23-Degree CNC-Ported Iron Cylinder Heads are derived not only from the precision CNC-porting of the intake and exhaust runners but the CNC-ported combustion chamber, as well.
Before CNC machining even occurs, these revolutionary cylinder heads are designed using the RHS' exclusive Clean Cast Technology to deliver superior port-to-chamber transitions for greater airflow. The CNC-ported 228cc intake and 82cc exhaust runners optimize volume, atomization and velocity while the 69cc combustion chambers are CNC-ported to relieve valve shrouding that occurs in "as cast" chambers when the edge of a valve is in close proximity to the combustion chamber wall.
The 2.055-inch multi angle intake and 1.600-inch radiused exhaust valve seats allow for superior airflow, thereby significantly increasing horsepower. In addition, these 23-degree SBC heads feature a refined water jacket for more even water flow to reduce engine "hot spots" and an extra-thick deck to allow angle milling. The thick deck surface also improves head gasket retention in boosted and nitrous applications.
In addition to these heads, RHS added two new part numbers (12328 and 12329) that will be available by the time you read this. Based on the Pro-Elite SBC head, these new part numbers are designed for Limited Sprint applications, 358 Modified, or any iron-head class that doesn't require a stud mount rocker. These new heads require an offset rocker arm since the pushrod window has been widened to reduce the restriction. In addition these two parts also come standard with a ductile iron intake and exhaust seat insert which is more forgiving with the alcohol engines due to the lack of lubrication in the fuels
For racing classes that mandate cast iron head use, RHS has designed a truly innovative head that utilizes the latest in technology.