My rule of thumb (and many other people's rule of thumb) is a minimum of four hours for "connections" on separate tickets (that's without checking baggage). If it's a small airport, and one I know well, and I don't have to go through Immigration or Security, I might be willing to cut that down to three hours, but probably not if there is a long-haul flight at stake. I wouldn't risk 1:40, especially not if one my onward flights is a long-haul one.

So - my advice would be "don't do it". Travel the evening before and stay overnight.