I've been rebuilding my engine from changing my head gaskets. I'm going to try to keep this simple. My crankshaft is only spinning 3/4 of a turn manually and when i get to that point i can hear a banging sound coming from the back of the motor, possibly the transmission. My 2 heads are rotating really good. Just not too sure what to do from on.

 

Welcome to FTE.

You are doing a "rebuild" with the motor in the truck, transmission attached, right? Did you fiddle with the trans or torque converter?

You say the cams spin. You should get very little cam rotation--only 3/8s turn from a 3/4 crank rotation.

Pretty sure you should not be spinning the cams or crank independantly in that motor.

IF you are all chained up etc, check to make sure you do not have a cam out of synch with the crank, "180 degrees out" as they say. In other words opening the valves at the wrong time.