Billy Woolfolk wrote in message <64ok9i$hie$1@blackbird.asahi-net.or.jp>...

>I have been developing my own black and white film recently with fair
>results; I haven't bougt an enlarger yet but at least now I can look
>at the negatives and decide which ones I want printed before I put
>them in.
>
>I develop my Tri-X, ISO 400 film for 8min at 20 degrees C, according
>to the box. On dark and rainy days, I would like to push my Tri-X to
>800 for a little more speed but I don't know whether I would then have
>to change the developing time, the temperature or both.


In my experience, there are two fine developers for Tri-X (for highest quality [fine grain, good sharpness, nice tonality, good speed] - for easy printing with dependable results): D-76 used 1:1 with the developing time reduced some from recommendations (best quality, at a true 400-speed), and Acufine used as recommended (somewhat lower quality, but at a true speed [with normal contrast and good shadow detail] of 800). Remember that pushing or pulling film changes overall contrast more than it changes true film speed (which is based on shadow density, not over-all negative density), so development adjustment is more suitable for getting the printing contrast you like than the density (which should be obtained through exposure, if you are after the highest image quality...). A rule-of-thumb is that for every stop increase in "speed", 1/2 again as much development is given - and for every stop of reduced "speed", 1/3 less development is given (though this only works well over a short range...).
Hope This Helps
David Ruether - http://www.fcinet.com/ruether