A lot of good ones already, here's some more I didn't see listed while glancing at the posts.
This Old Tony - great machinist and general projects, super dry, witty, sense of humor, really entertaining.
Allen Millyard - He's had a sparse channel for a long time, but has recently been going into some detail about how he grafts bike engines together, turning 4 cylinders into 6 cylinders, turning a single into a twin, etc.
Off the Ranch - Same guy as Demo Ranch, I pick and choose the episodes, and fast forward a lot, I don't particularly care about his family going grocery shopping, or what they had for breakfast, but if you weed that stuff out, there's some good stuff, i.e. recently he's been rebuilding a flood damaged C4 ZR1, setting up a new shop, and there's a whole series on a abandoned mansion he bought and is renovating.