Access 97 - importing file problem

I am importing data with extension file type of "file" into Access 97. The DB doesn't recognize this as a valid file. Tried to change this to a TXT file and it did convert only all fields came in as text format. I need to do mathamatical calculations between fields and text will not compute. I tried to change back to number those fields and the data was deleted.
I finally got it to work by opening it in excel and saving it as excel file but this is lost productivity. What can I do to import direct with mixed field names. In addition, Excel may have 20,000 rows and Access will only let me bring in 16,383 records. I have been having this problem constantly. One of my other DB's doesn't have this problem I can bring in 65,000 from excel but current files only let me bring in 16,383 records at at time I have to break up the lines to other sheets to input the data.