This guide can help you understand what valves your Predator engine came with. This is NOT an absolute guide as some parts could be changed when the engine was produced. To be certain you will need to measure the stem and face diameters. Gen 1 Predator (non-hemi); 5.5mm stems, 25mm intake, 24mm exhaust. Gen 2 Predator (HEMI); 5.5mm stems, 27mm intake, 25mm exhaust. Gen 3 Predator (non-hemi); 5mm stems, 25mm intake, 24mm exhaust.