Douglas DC-7 Question

This is a longshot, but I have a quesion concerning the DC-7 that tech
manuals and archives I've searched have failed to answer...

When the _very_ early DC-7's were delivered to United and American
Airlines, there was a small "scoop" visible just behind the main air
intake on all four engines. The scoop helped aid deicing of the carb.

Almost immediately this small scoop was removed and later production
aircraft did not have them.

My question is: Does anyone know WHY this mod was removed and WHERE
could I be steered online to maybe find someone who would know?

Please email me with suggestions.

Thanks, Danny   8-)