7 The metering blocks from BLP have jets in all of the fuel circuits, so making adjustments to the fuel curve is quick and easy. The 5120 series metering blocks wasn't a simple bolt on since these blocks are substantially thicker than a Holley metering block. The additional thickness meant we needed to make custom levers for the accelerator pumps. We also needed to acquire longer fuel bowl screws from BLP. The BLP metering blocks also required that we alter the air bleed sizes and locations. The outside air bleed now feeds the intermediate circuit, while the middle one feeds the idle circuit.