I'm looking at buying a Edelbrock carb, 850cfm # 1910. My manifold has four holes, two small and two larger ones. Meaning it's not a spreadbore or one large square opening. Will this carb fit without needing an adapter? Another question, when I try and "move" the back throttle plates with my fingers, they don't move. Is this normal? The front move when I "work" the butterfly. Thanks!