I have a early (66) 383 Mopar, pretty much stock, and just installed a Edelbrock 1406 carburetor. Timing set at 15 and 36 degrees. The motor had a flutter under slight acceleration between 1500 and 2200 RPM, with the vacuum hose connected to the "Timed Vacuum" port on the passenger side of the carb. -- I moved it to the "Manifold Vacuum" port on the driver side of the carb, and readjusted the idle, downward. I also moved the accelerator pump bracket from the middle hole to the hole nearest to the carb body (increased the squirt), and the flutter went away.. -- I moved the pump bracket 1st - slight improvement -- then switched the vacuum hose - presto, problem gone. -- Timing, vacuum, and carburetors are something that I am not very adept at, so please don't shoot Me. There are many different opinions regarding where to hook the vacuum to the carb. -- Have I done something wrong, and just got lucky -- or -- ???