[Bob Hinz]

Sounds like you have a bad ground. I would check the gound wire that attaches to the block. Take it off and check the wire and clean the block where the wire attaches. There should be another wire that comes off the ground terminal of the battery and attaches to the body. I would check that and clean where it attaches. Need to make sure you have a good metal to metal connection. You might have another wire coming off the block and attaches to the frame. I just check my 72 chevy and it looks like I don't have a wire from the block to the frame. Hope this helps.