Really thought I had answered this. What I meant by not throttle bore sized is that there is not one for a 600 cfm holley or 650 eddy or holley or for a 800 cfm eddy or holley. Get the idea? there is just the one for 4150 series holley which interchange with the eddy. 4150 holley equals eddy. They do how ever have them for different style intake manifolds. pick the one that comes as close the the design of your manifold and for the 4150 series carb.