Buildcraft version: 7.99.7
Forge version: 13.20.1.2429
Link to crashreport or log (on pastebin or gist, please don't put the entire log here) :
Singleplayer/multiplayer: Don't know if you need it yet...

Additional information:
I recall that in earlier versions, the quarry seeks blocks instead of doing a blind scan. It looks like it is wasting time trying to mine air. I can provide a save file if needed.

Duplicate of #3776.