Wilson CNC machined aluminum carb spacer, design for 4150 Holley models, increase low and mid-range torque for circle track cars that spend a good time part throttle. Radius tapers boost carb airflow by as much as 100 cfms for increase torque and throttle response throught out the RPMĀ range and as much as 20 more horses power. spacer 2″inch tall. Please e-mail with questions.