So I bought a timing chain set, replaced a head with some bent valves and installed the set according to a manual I bought along with many videos I watch while the engine was in the car. No easy task. I have the timing cover off and was baring the engine over to make sure no was obstructing the engines rotation. It will not turn over completely. It stops. I'm pretty sure there are no more bent valves and the timing is installed properly. Could there be something I'm missing?