Ecotec Exhaust & Airflow

How HF35.6 material, manufacturing sequence and installation decisions relate to the finished intake valve.

Understand head diameter, stem diameter, keeper location and the measurements needed for HF35.6 installation.

What BK Racing’s approximately +10 CFM prototype result at .050-inch lift tells us, and where its limits are.

Compare intake valve diameter, profile, material, nitriding and tip options before choosing an Ecotec valve.

A complete guide to Ecotec intake valve sizing, HF35.6 geometry, stock and extended tips, flow-bench results, installation and supporting valvetrain parts.

Running reground Ecotec cams changes more than lift and duration. Learn how reduced base-circle diameter affects rocker geometry, lash and valve stem height—and why BK Racing developed extended-tip valves and...