just changed engines put every thing back together hooking up battery got ground on went to put positive cable on engine started to turn over ignition is off and keys are out help please

 

Year model engine? Not much to go on here.

 

74 350 chevy in 85 camaro Z28

 

I would suggest disconnecting the wire from the ignition switch at the solenoid, then reconnect the battery and check this wire for 12V to a ground. If you find 12V there without the key "ON", you're going to have to trace the circuit to find out where it is getting it's source from. If the starter still turns over with this wire disconnected, look to see if the drive is somehow mechanically holding the solenoid contacts in a closed position allowing the starter to energize.