Why is it that your car always runs the best right before it breaks? The first pass it ran 7.561/89.51 with a 1.628 60 ft. The next pass was a mind blowing 7.477/90.89 with a 1.616 60 ft. The next run the magic smoke appeared and that put me on the trailer. The head gasket blew again (3rd time since last year) because the melted head weld repair is not holding. The question is......why does an engine run so good right before it blows?