Wood – straighten a twisted wooden pergola post

Here is the answer to my actual question:

http://awc.org/codes-standards/calculators-software/spancalc

Edit: Sorry if I'm not on the same wavelengths as anyone else. I already know about insurance and inspectors, and that was not at all what I was asking about. I just wanted to know what length of wood would span a certain distance given various criteria. I would have expected an answer to that question, instead of all the "your a dumb homeowner who's going to get in trouble" type replies. I question the idea that there will be 50psf of weight from snow given the fact that it is an almost non-solid top, and saw no real attempt to answer my question, so I had to come up with this. It took me awhile to find, and I hope it helps others.

Prior to drilling the "through-hole", mark the location on both sides and use a paddle-style wood boring bit slightly larger than the O.D. of your flat washer, to make a large flat-bottomed hole.

Make the holes no deeper than necessary to make the nut, washer, and bolt end sit flush (you would need a shorter bolt).

For more precise creation of a flat-bottomed hole you could also use a Forstner style drill bit, but they are significantly more expensive than a paddle-bit. It depends on how nice and clean you want the hole to be.