Heres what I did.

First, put negative on the good car to negative post
Then negative on bad car to negative post (or so I think)
Put positive on bad car
Put positive on good car, got a spark.

Turned good car on. Revved it a little and held it at about 1500 rpm. Tried bad car, nothin whatsoever, not even a chugchugchug. Gave it a few more seconds, heard a crackle. Checked it out, smoke. Then fire.