[428RA4]

Originally Posted by 65nss4spdGTO

Without speaking for Don, the factory style pushrod insert was an added obstruction to the port. With the ability to cast this requirement into the head, it allows for greater control in directing the air through the port. By casting this into the head, the port shape can be made to compliment the obstruction almost dividing the ports into two segments. Similar concepts are used on 4 valve cylinder heads.

Calvin Hill
Hill Performance
708-250-7420

Calvin -

Thanks for your thoughts. Though it may be a better control for airflow, I'm wondering if this design would limit your ability to port the heads. After all, it's now twice as hard to smooth out surfaces.