1990 Geo Prizm starting problems

Lets say I have been driving all day when it is very hot. When I cut the car off every now and then the car wont start. The lights on the dash board come on but the car wont crank at all and if I leave it there for like an hour it will eventually crank over or if I get a jump or use the jump starter it will crank over. I have changed the battery/ alternator and I have tightened the battery cables very tight so can anyone help me with this problem thank you.