I just put together my 70 Impala, it's almost time for Car Craft Nationals up here in Minnesota, and I cant get a belt to stay on my motor. I kick er down n she say's peace.its the belt that runs the alt, and water pump. why does it do this do i have it too tight or too loose, i thaught i had it tight enough but i dunno its blown 2 off and snapped one.