Hi group, I have a 1965 Pontiac 326, bone stock, with a Rochester 2gc carburetor. The engine is freshly rebuilt and I rebuilt the carburetor myself. The engine runs like a top except for one problem. When the engine is running the throttle body gets very tight. So tight that my strongest spring combination for the throttle return is barely enough to return it. Or if it is it's too tight to press with your foot. This kind of throttle body assembly has no return spring built-in, but that shouldn't matter with the external throttle return spring set up. The thing about this is that when the engine is off, the throttle is very loose and easy to move. I took the carburetor off a little while ago and looked over the whole throttle body set up. There is no binding that I can see at all and it works perfectly easy when the engine is off.