I've got a problem I need some advice on. I have a 1931 Standard Eight that I acquired as a stalled 30 year long restoration. I pulled the plugs, put about a tablespoon of Marvel Mystery Oil down each cylinder and let it sit a while. The head had some carbon in it, and the cylinder walls looked fine. I then rotated the engine about a third of a turn which went fine, no binding noted, then let it sit about two weeks. I come back and try to rotate it more, but everything is stuck. Tried putting it in gear with gentle rocking, but didn't work.

Given I was able to get some rotation, I believe I have something stuck on the valve train which didn't get stuck until the cam lobe came in contact with the stuck valve. I pulled the valve cover and hosed down where the valve stem contacts the lifter with PB blaster and additionally hosed down the tops of the valves in the head with PB as well. What more can I do here?