The First 5mm Stem Stainless Steel Valves For The Tillotson 212R, 225RS, And Predator Non-Hemi Heads! Stock replacement for Tillotson 212R and Predator 212 Non-Hemi. When we designed the Tillotson 212R, We decided to use the same 5mm valves as the Non-Hemi predator for the Tillotson cylinder head. Not only was the head diameter larger, but they were lighter than the 196 clones, Honda and Predator hemi valves. Tillotson would use the same head for their 225R/RS Engines with stiffer springs. Unfortunately, they kept the stock valves, which would not be suitable for stock appearing and modified running bigger, more aggressive camshafts and higher spring pressure. Without any aftermarket valves available, we took to having our own valves made to support the Tillotson and Predator heads. The smaller valve stems saves weight over the 5.5mm valve stems. Less weight means more rpm with less spring pressure. There is also a potential for better flow by reducing the obstruction in the bowl and choke and choke an area of the port. The Valves come nitrided on the top of the valve head and stem to protect from heat and wear. These valves are +.050 longer than stock valves to allow more lift without coil binding. This will change the spring pressure of the springs, so you may need to add a .050"shims to the springs bottom to have proper spring pressure for lower lift cams.