They either get along very well (if the INFP's values mesh with the INTP's thinking process) or would clash greatly (if they don't).
One of my best friends is an INFP, and we share many values, so we really understand each other. But INFPs who haven't developed much thinking-style functions can quickly frustrate me.
There is a decent chance that he is INTP, focused on some of the more tangible sciences. He could be ISTP as well: ISTPs will probably feel "harder" compared to INTPs, that might help you figure it out.
I have never had a problem with your INFP status.
He's also your father, so you share some values, you've spent years together i a 'forced commitment,' and so this has given you the opportunity to grow together, even if you are different.
In practice, INTPs seem to get more passionate about how people logic through to their answers. If they have a pet project, they might actually talk some about their conclusions. INFPs tend to express their values more, although they still are concerned that people are not being ethical on the surface but actually are ethical because inside they are changing.
Another quick test: INTPs usually get more mad at people's stupidity (usually in trying to put things together that will "obviously not work"), while INFPs lean more towards anger at people who are unkind or immoral.
But all of these things must be considered together, there is no silver bullet test.