Rhoads 8178X V-Max Anti-Pump Flat Tappet Lifters Set for Chevrolet V8or all racing applications. V Max Variable Duration Lifters are the answer. They increase low end torque and engine vacuum up to 50%. Typical vacuum increases range between 2 to 4 inches at idle when used with bigger cams. They are fully adjustable and require an adjustable valve train. Adjustment is similar to solid lifters. Simply use a feeler gauge to adjust the exact amount of lift reduction you want, anywhere from . 010" to . 040", and that is