Casting number 3978487 refers to a cylinder head used on the 5.7L (350 cubic-inch) small-block Chevrolet engine, commonly known as the "Vortec" head. These cylinder heads are known for their larger intake and exhaust valve sizes compared to earlier small-block Chevy heads. The valve sizes for this casting number are:
- Intake Valve: 2.02 inches (51.3mm)
- Exhaust Valve: 1.60 inches (40.6mm)
These larger valves improve air flow into and out of the combustion chamber, resulting in better engine breathing and increased performance potential.
