In Longman dictionary, it says that:
"you would have thought (that) "(also you would think (that)) used to say that you expect something to be true, although it is not
Here are my examples, I don't know if I can use "would have thought" and "would think" interchangeably for a past action:
Example 1:
A:Tom failed the exam.
B: (1) Really? I would have thought that he passed the examination.'
B: (2) Really? I would think that he passed the examination.
Example 2:
John: I gave the waiter a $50 dollar tip and he gave me a dirty look. Maybe I should have given him more?
Bill:(1) No, $50 is enough, I would have thought.
Bill:(2) No, $50 is enough, I would think.