ange-ftp-ascii-hash-mark-size

ange-ftp-ascii-hash-mark-size is a variable defined in `ange-ftp.el'.
Its value is

1024

Documentation:
Default size, in bytes, between hash-marks when transferring an ASCII file.
This variable is buffer-local and will be locally overridden if the FTP client
outputs a suitable response to the HASH command.

You can customize this variable.