You can get these data from MAST but it's not terribly obvious. Once you have filtered down to the data you want, selecting the data for download will produce a box that allows Uncalibrated file types to be returned. Searching the MAST archive for Hubble Space Telescope(HST) data from the Advanced Camera for Surveys (ACS; which contains the Wide Field Camera (WFC) and High Resolution Camera (HRC) you seek) in the specified filter (F814W; a W
ide F
ilter, centered at 814
nm) for galaxy data (MAST query URL) should produce a display that looks like:

Selecting data that you want to download (tick boxes on the left side; note this search was for public data so data that is still within its proprietary period after being taken and therefore only available to members of the proposal should not appear in the results) will produce a 'Download Data' button:

Clicking the 'Download Data' button will (might take a while if you have lots of datasets selected) bring up a dialog box which allows you to select 'Uncalibrated' and/or 'Reference' to see those file types along with the pipeline processed calibrated images (note the _raw
and _spt
FITS files options that have now appeared):

Selecting these will result in those datafiles being added to your downloadable dataset. HST documentation and the Instrument and Data Handbooks for all the current and past instruments can be found here. In particular the ACS Data Handbook has a Section 2.1 (Types of ACS files) which explains what the many suffixes mean. There are a lot of processing steps that occur to the raw data before pipeline products are delivered to the archive which are outlined in the later chapters of the ACS Data Handbook - it is strongly recommended to read these to understand the processing that was done and the calibration files needed if you are trying to replicate it, particularly for HST data (which has a lot of cosmic rays) and ACS data (which has significant geometric distortion). There is a section on manual recalibration of ACS data which makes use of Python.