With the AC on the temp goes up steadily, no matter if it is idling or going down the highway. Lower hose is new and has the spring in it. I will check on the Radiator and put my scope down in it to check the tubes when I swap out engines. The 4 row is supposed to handle a lot of HP, and the 434 is going to be capable of a lot of HP... Both the fellow I ordered the cam from and the people I got the engine from, it should be 1000HP+ with the nitrous. I am not that optimistic, and if it is that stout I will probably not even fill the nitrous bottle.. just leave it in there for show!