I will recommend to take an earlier flight to avoid missing your connection.
The problem is going thru the security check. I just came back on NW from HNL. There is a 30 - 40 minutes waits to go thru the security check at LAX. If you count the time you catch the bus from UA terminal to NW, and NW required you to check in at least 20 minutes before the depature, you are really cutting close.