Hey guys, I've got an issue with a power steering rack on a '37 plymouth coupe I'm helping my father in law restore.  After everything is hooked up & the system is bled, when we fire the engine & touch the steering wheel, the wheel begins to jerk uncontrollably from left to right.  This is a ford mustang II front end & rack with a ford *** pump on a 350 chevy engine.  Any help diagnosing this issue is greatly appreciated!

Adam