Here are the two carbs we tested in our final session. The HP series features streamlined venturies for better air velocity, screw-in air bleeds for added tuning possibilities, and notched floats for jet extensions to help prevent fuel starvation. From the top, the 750hp and 950hp look almost identical, but turn them over and you will see the difference in throttle-blade size; the 950hp (left) blades are closer together and drilled to improve idle quality on engines with radical cams. The more streetable 750hp features ported PCV and vacuum advance outlets. Both have Holley's new four-corner idle control layout.