I'm in the process of reassembling my engine and just installed my new water pump which is from Dave Bean. I went to install the new thermostat and it won't fit into the recess in the top of the water pump. When I measured the diameter of the recessed area in the water pump and the diameter of the thermostat it turns out that the recessed area in the new water pump is 0.010" less than my old water pump and therefore too small for the thermostat to drop into place. Has anyone run across this issue before and if so, what did you do about it? I was thinking I could just file off 0.010" from around the outside of the thermostat. Wondering what others thoughts are on this issue.
Haven't seen this problem in decades but it was not unheard of in the early days of foreign-made auto parts. In any event, the short answer is yes, provided you don't create any sneak paths for the coolant to bypass the thermostat. For the upper (locating) disk, Wellseal or Permatex will help ensure that. For the movable (valve) disk at the bottom of the thermostat, you need to remove material equally around its entire circumferance.
For this sort of task, I've found that emery cloth over a stick is generally a better tool choice than a file.