[You Need a Thneed]

A beam is only as strong as it's weakest point, and you have a spot where the beam is only one ply.

I'd definately want to make that a three ply beam.

You spent more on carriage bolts than they extra ply of 2x8.

Ideally, you want splices at the supports, or at the 1/3 points between supports (not right in the middle). In a three ply beam, you should never have two plys spliced at the same point, other than directly on top of a support. Every piece of every ply would ideally span at least two supports, but at least on one support and two thirds of the way to the second one. Short pieces at the end don't help very much.