I have a 1974 corvette L48 I bought the other day. I put it in the garage and then when I went to start it a few days later the car seems likes its dead. (however the battery is fine).  I have no idea what couldve caused this, the car would fire up perfectly when I would start it before. When i turn the key now, randomly, the radio and acc. will turn on, but most of the time its like everything is dead. When the radio, acc., etc does turn on and you go to turn the key farther to start it, it kills everything and seems like there is no power to the car at all. I replaced the ignition assembly today in the steering colum with the same results... can anyone help?????????????????

Sounds like a ground - I agree with Scott. I would clean and tighten all battry connections and see what happens.

Yeppers...most likely a loose/corroded battery connection. Check those connections first, then the ground connections. The fist ground connection is the cable from the battery to the frame. It is attached to the frame just behind, and under the driver seat area. The other major ground is a cable from the frame to the engine block, on the passenger side, right where the engine mount is. Check those out carefully.
Another problem area is the positive cable from the battery to the starter solenoid. Check to see that that cable is also nice and snug...it can work loose, and cause the exact issue you are having. Be sure to dis-connect the negative battery cable from the battery before trying to tighten the nut on the starter solenoid...if you don't, you'll have lots of sparks flyin!
Welcome to C3VR, too!
Adams' Apple2010-06-14 19:51:45

I agree with all the others. The connection of one of the batery cables is poor, but enough for small amp loads like the radio. As soon as you hit start the amp draw opens the connection. If cleaning the cables doesn't correct it check for corrosion under the insulation of the battery cables near the battery terminal ends. If the wire is bulged out it is corroded and will need replaced.