Hand milling cutters/ spherical cutting for cylinder-head porting at home and is something a novice can accomplish to wake-up engine power. Material HSS – HRC 62±1. Cutter – 1ps. Mandrel L200 – 1ps. Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve their air flow. Cylinder heads, as manufactured, are usually suboptimal for racing applications due to being designed for maximum durability. Answering the most common question we getting. WHAT ABOUT THE WAR? / What is your status during the war? Can you do custom reamers? – Unfortunately, now we do not take individual orders, we have accumulated a lot of work, you can send a drawing, we will consider it, but not earlier than in a month.