Just dropped in a motor in my 91 vert and when I turn the ignition key to "on" the temp gauge goes straight up to the H area. Is something not connecter or loose? Also, my airbag light is blinking now and it wasn't doing this before. Thanks.

 

is there water in the car.

 

Is the car started or just in the on position? If it is not an engine problem, then is sound likes maybe one of you temp sensors are not conected.

 

The wire to the water temp sensor is shorting to ground somewhere, or the temp sensor is bad. Assuming the guage isn't bad, those are the only two things that will cause the guage to read full "H" as soon as the key is put in.